Well, this is a old thread but just wanted to share my experience. I have a '93 with 165,000 miles on it. I've always used Mobil1 dino juice and change it every 2000 miles(yes, 2000 miles) with a new K&N filter but for some reason all the local places stopped carrying it. So, I switched to Mobil1 Synthetic. I haven't noticed any leaks yet but it seems to have cured a rattling noise I heard on cold startups every once in a while(sticky lifter?).
So far so good.
I believe that regular mineral oils provide very good protection if changed at reasonable intervals. I used to use regular oil and I changed it every 3000 miles. I switched to Mobil 1 just so that I could go an extra 3K without the hassle of changing the oil (6K with full synthetic is waaay overkill). To me it's well worth it.
Believe it or not, and FWIW, I have 279K miles on my '89, no engine work whatsoever, burning 1/2 qrt every 3K miles, and that is on Penzoil oil and Fram filters (before I knew any better).
Am I just lucky or is all the talk on synths, etc, just a hype? I could be completely wrong on this, but I think regular oil/filter change goes much longer way than brand/blend of oil/filter used.
My 0.02 ... Maz
I don't think it's hype. I think part of it is that you've been dilligent about changing the oil and using a quality product. Part of it is also that the 4.0 is a great engine.
I use Mobil1 on anything I care about. I have converted many cars at 100+K miles from dino oil to full synthetic and have been pleased every time. No leaks and in one case far less oil consumption....go figure.
I just changed over my 1995 Toyota Corolla with 105,000 miles to synthetic and change at 15K intervals (mostly highway). Oil is brown but not filthy when removed. This thing will still be purring when at 300K.
I think that if your engine does not burn or leak oil you should be fine. If it does leak or burn oil after going synthetic...just go back to dino...no harm done.
One FYI. I did read that roller rockers are not too happy with synthetic. Apparently the oil is so slippery that the roller slides rather than roll and causes unnatural wear.
Mobil 1 full-syn high-performance and a new filter every 3 thousand. For me, I give nothin but the best to the love of my life. Much of the benefits of synthetics have yet to be discussed. Due to the reduced friction, they help cover engine parts better, absorb heat better, and my favorite, actually add a couple ponies. It's a matter of the vehicle, if u really care, I think syn would be better. For the a to b daily driver, there's nothing wrong with the dino oil.
Correct, M1 does all that and more. I have seen several dyno runs of cars running no mods with just M1 in the engine and got a 5hp gain in the mid to upper rpm bands, and it was consistent after repeated tests. I have seen dyno runs on vehicles where synthetic was put into the engine, tranny, tcase and diffs and there was an 8hp gain on average.
