I think I'll be converting my 89 4runner (22re engine with 175,000 miles) over to synthetic, but was curious what your personal experiences have been with it.

vmax84

 

I switched my Honda accord over at around 20,000 miles and got a leak from the rear main seal. Switched back to conventional oil and leak quickly disappeared. Switched back at 62,000 miles from everybody chanting about the theory of synth causing leaks is BS. Guess what.....the leak came back. Switched back to dino, but this time it took a several thousand miles and a couple of oil changes before it slowed down. Now at 74,000 miles it still leaks a little.

On the yoty, I added a quart of synth to 4 quarts on an oil change to test the waters. I immediately got a leak coming from somewhere in the rear area of the motor. Changed the oil with pure dino and the leak substantially decreased, but it's still there.

My opinion? No worth it all!!!!

Now, when I rebuild the 22re I'll give it try, but not with 22 year old gaskets!!

 

Have you [searched] yet? Theres tons of reading already posted about this subject.

 

I switched my 4Runner at about 95,000 to Castrol Syntec. Don't know what the previous owner used. No leaks. Switched to Mobil 1 sometime before 200K now have leaking rear main. Just filled the crankcase with Castrol High Mileage to see if that takes care of the leak. I really don't want to spend the $400 the dealer wants to replace the rear main seal (although their price is pretty reasonable).

I had such good experiences with Castrol Syntec and was always a little disappointed with Mobil 1. Everyone will tell you that Mobil 1 is full synthetic and Syntec is just a more highly refined dino oil, but it kept my Corolla running hot as a dime store pistol until I sold it with over 250K on it. I think I'll either stay with the Castrol HM or go back to Syntec.

On a side note, the guys on bobistheoilguy.com have been ranting lately about the high quality of Havoline dino. Seems to have more moly in it than most other oils.

 

Honestly at that mileage, just keep using a good quality dino such as havoline or castrol GTX and change it every 4k-5k. You won't really gain much with syn.

Just my opinion.

 

I just swapped my 270K miles 87 22RE over to synthetic, Royal Purple, in the engine, diffs, everywhere, doesn't leak a drop.

IMO, a leak in a gasket/seal is a leak, regardless of what oil/fluid you are using.

I think you'll be fine either way, as it has lasted 175K so far on dino oil...and there are TONS of threads about synthetic oil...so please do try searching next time. A personal response is nice, but you'll get less and less responses if you keep asking redundant questions.

Good luck.

 

Mobil-1 experiences, huh? Well, my wallet feels violated!

 

Almost 10k since the last change (wife won't take it in for service), no issues. Am changing it tomorrow night so I don't have to use the dealer. Switching to Amsoil after this.

 

I can never tell the difference between my oils. I ran a havoline synthetic for a while (15k? and a few changes) and everything was fine. A few hundred miles ago I used mobile 1 because it's supposed to be better. Everything is still fine.

I typically think of the price diffence in oils to be no big deal at all. I mean you don't buy it all that often and it's only a few dollars. However, this last time I put mobile one in my V6 taco, my wife's focus, and I bought gear oil for the taco's front/rear diffs and manual transmission. That's a *lot* of money for a boatload of oil. The cost really did make a difference, especially for the gear oil.

I guess I'll keep running mobile 1 but I don't have an oil analysis to prove why I should.

 

M1 syn held up great in my Eclipse which was drag raced for 8 seasons but I ddin't let the oil get much older than 3500 miles due to it having to protect a hard driven turbocharger. (actually protected 3 of 'em)