what oil to use

[WB9YZU]

Here's my .02C.
Having used both synthetic, regular oils in racing applications and having worked on AC engines where synthetics were introduced.

Yes, the synthetic oil generally lubricated better, adheres to surfaces better and more stable (both physical and thermal). As a matter of a fact, I had an engine saved IMO by the use of synthetics when a new oil pumps bypass stuck open durring a WOT 1/4 mile pass. You can run a lower viscosity and still get the same lubricating properties as a higher grade of regular oil, thuse creating less windage loss and better gas milage. My race engines had a set of passes with regular oil (to seat the rings), then from then on, it was synthetic.

General AC engines had a hard time of it when it was introduced.
These engines get outstanding mantance, far more often than your standard car, but,
they burn leaded fuel and generally had been using straight weight oil durring most of their service life. Mobil 1 was introduced and all heck broke loose. People thought, 'hey, more power + longer life' but the opposite happened because the oil cleaned better and broke all the junk loose. Bad news. The oil was refined and most General AC users run a synthetic blend, something like Valvoline "Dura-Blend" but more robust. Still darn expensive

That asside. Changing your oil often (one user said he changes every 1,500mi) will do wonders keeping your engine sludge fee with ANY oil. All oil obsorbs the nasties that go with burning gas, so a regular oil change at 3K is recomended for all oils.

This whole thread comes down to one thing, and one thing only. With a high mileage engine, is it worth throwing $5/qt oil at it? I wouldn't.

The best thing I have found so far to extend the life of my engines is to change your oil, use a good oil (I use 10-30W Valvoline myself), and to change it every 2,000 to 3,000 depending on service it sees. Same thing with your transmission, axles, whatever. You want it to last? Do the mantance - and if you pound on it - do it more often.
,Ron

 

[homebrew]

Well I switched to royal purple. previously I was using Qstate 10-30w with the addition of hyper lube, which I noticed helped calm the engine when I first got it. Sense the change to synthetic I now have a tick in the bottom of the engine. It is not constant but really annoying. it will tick like ten times then go away, really unpredictable. I was thinking of adding a quart of thicker oil to see if that will help quite the noise. Any thoughts???? what might that ticking be???? On a good note I have had no oil leaking from the seals, I was really worried about that.

 

[Rick Anderson]

....That asside. Changing your oil often (one user said he changes every 1,500mi) will do wonders keeping your engine sludge fee with ANY oil. All oil obsorbs the nasties that go with burning gas, so a regular oil change at 3K is recomended for all oils.

If I only drove my car 5 miles a trip, then I would change the oil every 1,500 miles. If I drove my car 500 miles a trip, then I would change the oil every 15,000 miles.

If I only drove my vehicle off-road and on trails where the rpms where always high and there was nothing but water/dirt/dust and mud being thrown on and around the motor, I'd change my oil every 1,500 miles. The dirt, dust and moisture does work its way into the motor and contaminate the oil. As well as the rough running on the motor is tough on the oil as well.

Its the start-ups and running the motor cold that really kills the oil. The 3000 mile figure is a "Play It Safe" oil change period for the way "MOST" People drive their car. I totally agree with it, and oil is much cheaper than a new engine.

Often the oil is still good at 3k miles, BUT it can get contaminated for all sorts of reasons that most drivers will never notice, so changing the oil at 3k miles, garuantees that your motor always has good oil in it, for the way most people drive. i.e. For most people, changing oil at every 3k period, 9 times out of 10 that oil is still good and they could have waited longer, BUT 1 time out of 10, the oil was contaminated or bad and it needed changed then or extra wear would accumulate on the motor; thus play it safe and always change it when it "might" go bad and you can't tell.

If your car is abused with nothing but short trips that the motor doesn't even warm up fully, do it more often than 3k.

If your a traveling salesman, and 80% of driving is several hundred mile trips on the highway, than you go change oil less often than 3k miles and be just fine.

 

[dyna]

Some of your comments in I question, correct me if im wrong. #1 some oils do indeed have different and stronger detergent packages( how bout diesel oil or commercial rated CF/CG etc). #2True, if your engine is that gooped up it needs a rebuild, but putting in a solvent based additive probably will kill it sooner. #3 If you avoided letting your engine go to hell to start with you woulden have any of these problems, not dont never change the oil and the engine will never fail.

 

[jeepsrock]

My theory here is use whatever works well.

If you have been using dino oil for a while and you have a lot of miles then their should be no reason to switch to a synthetic oil. Switching to a synthetic oil on a younger engine can help it stay clean and provide slightly better lubrication. In an older engine synthetics can provide a mess of issues. Most common being leaks, different ticks and sounds and what not.

Also if u use dino fluids their are a few products to stay away from. Always stay away from specialty fluids like high mileage or 4x4 blends, these contain other chemicals that are not usually gonna help much. As for brands most are ok except for Penziol (sp?) and Quaker State, those will create sludge like no other oils and. As for filters stick with napa, wix, bosch, purolator and u should be ok.

Stick with what works.
pete

 

[50yearXJ]

this maybe a really dumb question, but is anyone running straight 40 weight oil in there XJ. My father swears by 40 weight for any of his vehicles, but his XJ is now behind the shed. Well, some of it is now on my XJ. I recently did an oil change and put Castrol HD40 in with a Bosch Premium filter. Stopped the clacking/slapping at start-up, which I was happy to NOT hear for once, but it sounds like everyones sticking with 10w-30 or 40. By the way it's a 91 4.0 HO with who knows how many miles. The odometer says 140,000 but there's also a red flag on the title and a trouble code related to the odometer. Basically....it's wrong. Any advice would be appreciated.

 

[Rick Anderson]

Some of your comments in I question, correct me if im wrong. #1 some oils do indeed have different and stronger detergent packages( how bout diesel oil or commercial rated CF/CG etc).

That is very true, the additives packages designed for oil are the results of years and billions of dollars of research by the Oil Companies and they do an excellent job for the particular application they were designed for. That is why you don't want to use diesel oil in gasoline engine, the additives package isn't taylored for that particular application and you can get undesired results, as well as be lacking the desired results.

So why would the oil companies create an additives package for synthetic oil for the application of gasoline engines that had a much stronger detergent package? Would they not taylor the additive package to give the same desired result, just like they do the gasoline engine? Why would they create an additive package for Synthetic oil that is so strong in cleaning that it can damage older gunked up motors? As well, why only for Synthetic Oil?

People assume Synthetic Oil has this incredible Cleaning Power, because motors that use it are so clean. That assumption is incorrect, Synthetic Oil does NOT leave behind deposits and has much greater resistance to forming sludge and crud, that is why motors that use Synthetic oil are so clean; the synthetic isn't cleaning the motor so much more, rather its just dirtys up the motor so much LESS than conventional oil.

#2True, if your engine is that gooped up it needs a rebuild, but putting in a solvent based additive probably will kill it sooner.

Thats right, so what synthetic oil or any oil has an additive package that contains solvents? I don't think I ever implied that, and I agree, adding solvents to any motor oil is risky, even a clean new motor, it thins down the oil and contaminates it.

#3 If you avoided letting your engine go to hell to start with you woulden have any of these problems, not dont never change the oil and the engine will never fail.

Thats right, thats why I change the oil often, use quality oil and use synthetic oil in my latest vehicles since the motor was broken in.

I was pointing out the flaw in the logic, if someone thinks anything that disturbs the dirt and crud accumulated in an old motor would put it at risk of failure from the chunks of dirt and crud breaking up, then logically wouldn't changing the oil and introducing fresh detergeant and oil give the same result?

 

[Rick Anderson]

this maybe a really dumb question, but is anyone running straight 40 weight oil in there XJ. My father swears by 40 weight for any of his vehicles, but his XJ is now behind the shed.

Depends on conditions, if you live in Arizona, you'd probably get by just fine with straight weight 40 or 30 oil. You live in Pensylvania, I'd think those winters would rule out straight weight 40 oil, not to easy on starting the motor.

An oil pressure gauge can tell you a lot. You oil pressure is higher than spec, and your using thicker than recommended oil, chances are the thicker oil isn't flowing as much volume as its suppossed to, that might not be too good. I'd stick to the recommended viscousity. If the motor has a lot of wear and lower than spec oil pressure than using a thicker viscousity can bring back some of the pressure, theres limits to that as well.

 

[Sarge]

That is very true, the additives packages designed for oil are the results of years and billions of dollars of research by the Oil Companies and they do an excellent job for the particular application they were designed for. That is why you don't want to use diesel oil in gasoline engine, the additives package isn't taylored for that particular application and you can get undesired results, as well as be lacking the desired results.

Go read the specs. Most diesel oils meet and/or exceed car specs. I've run Delvac or Delvac Mobile 1 in everything I own and have never had a problem. As a matter of fact HD recommends if you can't get their oil you run a diesel oil until you can.

On the other hand I've also run the real cheap stuff. I shorten the change intervals with the cheap stuff tho.

Sarge

 

[tvisXJ]

I use castrol GTX high mileage in all my vehcles.

 

[50yearXJ]

I've been keeping an eye on my gauges since doing the change. Oil pressure is a bit high at start-up, around 60, but as it warms up it runs right where it should. I had an OP problem this fall but did a change and slapped on a new sending unit and all has been well since. I usually don't drive it until it's up closer to normal operating temp since the engine is a bit worn. She needs all the help she can get at this point. Winters are a bit brutal around here but this winter in particular has been pretty mild and spring is right around the corner. I think I might keep the 40 weight in through the summer and go back to 10w-30 in the fall. Thanks for the input guys.

 

[DenLip]

The Cost of Synthetic is a valid aurgument, it is often overkill for most motors, with cheaper conventional oil doing more than an outstanding job of protecting the motor, but you pay 2-3 times as much for the oil, for protection that you really don't need in most cases.

Like a lot of folks... I run synthetic (Mobil 1)... but I upped the change interval from 3k to 6k at the same time. (with a midterm filter change and top-off). This brings the costs down to "negligibly higher"... $4.00/qt versus $1.79/qt... but only using half as much oil... and the same number of filters over time.


When I change the M-1, I don't notice any real change. When dino oil was changed, I always noticed that the engine ran quieter afterwards. That tells me that the M-1 isn't breaking down as much in 6k as the dino did in 3k.


We'd been running Castrol for years... for that same reason: Castrol seemed to hold up better than other brands.

Den

 

[Comanchedude]

I'm not much for these schools of thought about crud holding an engine together. Think about what this is saying. The motor is being held together by dirt and garbage, touch it the wrong way and it will all fall apart. Oookaay, but you drive all over the place with the same motor?

This is like the school of thought about transmission problems, where you get someone that warns you not to change the fluid and filter in a tranny thats not working right, because it might do something to the shifting that will only make it worse.

OK, sure its possible that changing fluid or switching to a different type of fluid could cause dirt to break free or changes that pushes your motor/trans over the edge and it fails or malfunctions. BUT, the fluid is not the cause, its the motor/trans being in such bad shape its was on its last legs and was going to fail any minute is the true cause of such a thing.

So guys, if you think dirt might become unlodged and destroy your motor from switching oil types, then rebuild your motor because it needs it. If switching to synthetic is going dislodge enough crud to damage the motor, than there must be enough in the motor already that it could break free on its own at anytime and do the same damage. Fresh oil will clean better than old oil, so by this logic, if I have a dirty motor, NEVER CHANGE THE OIL AND IT WILL LAST LONGER because you never want to take a risk of breaking some of that dirt free and having it float around the motor.

Synthetic oil does NOT have some miraculous cleaning property or high detergeant additive package to clean up motors.


Well said I was not going to even bother to post but I had to say your post is among the most inteligent and accurate one so far

 

[warwagon98xj]

I've switched to Synthetic in motors with more than 175k Miles and never had a problem. In fact, the motor ran smoother with less noise, like lifter tick.

Synthetic oil properties, like polar molecues, etc, does tend to flow more oil thru a leak. So, if the motor has lots of leaks, synthetic may make it worse. Give it a try, if it leaks to bad, then switch back to conventional oil, if your not willing to fix the leaks.

I'm not much for these schools of thought about crud holding an engine together. Think about what this is saying. The motor is being held together by dirt and garbage, touch it the wrong way and it will all fall apart. Oookaay, but you drive all over the place with the same motor?

This is like the school of thought about transmission problems, where you get someone that warns you not to change the fluid and filter in a tranny thats not working right, because it might do something to the shifting that will only make it worse.

OK, sure its possible that changing fluid or switching to a different type of fluid could cause dirt to break free or changes that pushes your motor/trans over the edge and it fails or malfunctions. BUT, the fluid is not the cause, its the motor/trans being in such bad shape its was on its last legs and was going to fail any minute is the true cause of such a thing. Its extremely rare, but if its happens, it was only brought on a few miles earlier than it would have happened if you done nothing at all.

So guys, if you think dirt might become unlodged and destroy your motor from switching oil types, then rebuild your motor because it needs it. If switching to synthetic is going dislodge enough crud to damage the motor, than there must be enough in the motor already that it could break free on its own at anytime and do the same damage. Fresh oil will clean better than old oil, so by this logic, if I have a dirty motor, NEVER CHANGE THE OIL AND IT WILL LAST LONGER because you never want to take a risk of breaking some of that dirt free and having it float around the motor.

All oils have cleaning properties and they also have the potential to create sludge and crud as a byproduct of their use. Using the proper oil and appropraite quality in the right conditions with a correctly working motor, the cleaning properties of the oil should outpace the byproduct production of sludge and crud.

If sludge and crud is building up in the motor, its because the byproduct production is outpacing the cleaning properties of the oil. It could be because of the poor quality of the oil, something is wrong with the motor (malfuntioning CCV system) or the conditions you use the motor in, or how often you change the oil.

Synthetic oil does NOT have some miraculous cleaning property or high detergeant additive package to clean up motors. Synthetic oil, since it so well engineered to do its job, contains very little of the byproducts that make sludge and crud, it resists breakdown much better to help fight it turning into sludge and crud, as well. This why motors running synthetic for a long time are so clean, they don't leave behind any deposits/sludge/crud like other oils. They may clean as well or a little better, but they aren't some sort of SUPER CLEANER, they just don't leave behind deposits like regular oil does.

If your motor is extremely dirty, switching to synthetic should clean it up, over time. If your motor is so dirty that switching to synthetic breaks free chunks of dirt that damages the motor or lets seals leak, then you motor was toast to begin with, the new oil only brought on the failure a few miles earlier than it would have happened on its own. Like I said before, fresh regular oil will clean better than old, as well, so wouldn't fresh oil have the potential to break off dirt chunks as well?

I've seen lots of speculation about what can go wrong when switching to synthetic oil in high mileage motors, but I see very little actual cases of people complaining of actually suffering any of that speculation. Instead you see a lot of endorsements with people saying that switching to synthetic was an improvement.

Weigh the pros and cons and decide on that, I just don't believe you should believe you should make decisions living in fear that your motor is being held together by dirt/sludge/crud and anything you do to improve it may make it fall apart. Its not going to happen, if it does (your that 1 in a million) then it was going to happen anyway, because the motor was ruined to begin with, you just didn't know it yet.

x2 and theres this neat thing 1/2 way down the block on the pass, side called a filter..........

 

[DeadSquirrel]

I normally run 6 quarts mobil 1 fully synthetic but last time i decided to go with 5 quarts mobil 1 and 1 quart lucas oil fully synthetic stabilizer. I love that lucas oil stuff and i would recommend it. my engine runs quieter and much smoother than with just the plain synthetic...i'm a believer in it...and by the way STAY AWAY from fram filters

 

[montanaman]

I'm not much for these schools of thought about crud holding an engine together. Think about what this is saying. The motor is being held together by dirt and garbage, touch it the wrong way and it will all fall apart. Oookaay, but you drive all over the place with the same motor?

I think that people are saying ... if your motor is filled with crud, you don't want large chunks of it breaking loose and circulating thoughout the oil passages. Not because the crud holds the motor together (of course not, nuts and bolts hold the motor together), but because those loose chunks of crud can clog an oil passage and starve a bearing or some other section of the motor of oil, causing it to fail.

It's kind of like the human vascular system. If you have a blod clot, and it breaks free, it might migrate to the brain and block some arterioles, causing a major stroke. Not a good thing, and that's why doctors no longer prescribe clot inhibitors or blood thinners to people who already have clots.

So ... if you have crud in your motor, that's not good. But loosening it all up at once could be even worse. I'm not sure what the ideal solution is. Some say to run mild cleaners through the motor over several changes to gradually clean it out, others say blast it with heavy cleaners like the GUNK brand motor cleaner ... with the logic being that a heavy cleaner like that will break up any chunks before they can clog a passageway. Which is best? I have no idea.

I just put in a remanned motor into my 4.0, and I'm running synthetic in it because it doesn't break down to form the crud in the first place, and does a superior job of lubricating. Is it cost-effective? I don't know, but if I was only doing the things on my jeep that gave me the most miles per dollar, then it would be a different beast all around. This is an insane addiction for me, and an extra $10 every 3 months isn't going to kill me.

 

[MyJeepXJ]

WalMart Supertec, but I change oil and filter ($10) every 2,500, religiously(Sp?).

 

[Rick Anderson]

WalMart Supertec, but I change oil and filter ($10) every 2,500, religiously(Sp?).

I've heard more than once that the WalMart Supertec comes from a Major Supplier that also supplies a lot of the big Name Brands, but I don't know that for a fact, suppossededly its quality oil that performs well.

Changing oil frequently is probably more effective than using the #1 top quality oil and filter. Just make sure to avoid the garbage quality oil & filters, like Fram Orange Filters. I don't know, but judging from the posts many people have a low opinion of Pensoil, I guess it has a lot of parafin in it and other bad byproducts.

 

[flexjay87]

buddy of mine and i went to Daytona this year and we drilled the guy at the Valvoline tent outside the track. friend and i had been discussing what kind of oil to use. to make a long story short the Valvoline guy said company policy was to always go by what the owners manual says for oil changes, basically 3k based on car manufacturers suggestion, no matter if it is synthetic or not. i called a couple of company headquarters and they say the same thing. one guy did say that moisture in the engine will kill the additive package of most oils. so always drive your car long enough to get it hot enough to burn out the moisture. i am sure they still love the profit from synthetic, especially if you change it every 3k. oh they also said time is just as important for oil changes as mileage if your car sets outside and you don't rack up many miles per month. 3k or 3 months is the rule of thumb.

 

[Rick Anderson]

I proper working PCV or CCV system removes the moisture and other corrossive fumes that create sludge and crud. Those that disable their system for a cooler looking mini air filter on the valve cover OR because they think its some sort of power robbing pollution control device are doing nothing but shortening the life of their motor.