I decided to switch to a synthetic oil at 89k miles. At first everything seemed OK. Driving around town and the occasional 100 mile trip produced no leaks. One day I was pulling a heavy trailer around town and noticed a few drops coming out of the rear main seal. I was pushing the truck pretty hard that day, so I knew why the thinner slicker oil was coming out.

This past weekend I made the trek from Reno to L.A. and back. On the way back I noticed a little smoke coming out the back. My first thought: Ah crap! my headers caught something on fire..... again.

I pulled over and looked under the truck. I was alarmed at the rate in which oil was dripping out. I let it cool down a little and got back on the road (I was in the middle of nowhere, what else could I do?). A few hours later when I got home I checked the level and had lost about a quart. Needless to say, I put dino oil back in the runner tonight.

It shouldn't leak anymore right? It didn't before the synthetic oil. Should I be worried?

 

i havent any idea about why it was leaking?? they leak for the dumbest reason and out of every orfice.

hmm i dont know what to tell you. i JUST switched 2500k miles ago and now have 143000 today. i havent had any leakage problems as of yet. YET!

 

Same here, I switched over at about 90K and I have 95K now with no probs. Maybe it's a sign of bigger probs which need to be dealt with ASAP.

 

Ive seen it happen on higher mileage vehicles, the syn seems to find cracks that the dino couldn't. Unless you think you have or can find a problem, i wouldnt worry about it. The syn eventually plugs up like the dino and quits leaking.

 

Synthetic oil has more detergents in it, "cleaning" the oil and gunk out of the motor passages, and if you had any gaskets that were worn, the synthetic always finds a way to remove the gunk from them created by the conventional oil, exposing the problem. Switching back isn't going to help you in the short run.
I've heard of many people switching in high milage motors and having this same thing happen to them. But some people get lucky.
Synthetic is superior to conventional, but if you change your regular oil at 3000 intervals, there should be a significant benefit. IMO
I would suggest having the gaskets replaced at this point.

 

Replace your valve cover gaskets. While there replace pcv, pcv hose and grommet. Its a days work since you have to pull intake plenum. Don't forget to get a new gasket for intake.

 

Ok I'm no oil or engine guru, BUT, I seem to recall getting cautioned quite sternly by a very knowlegable "Engine Guy" who told me that if I decided to switch to synthetic oil that it is best to stay with it and NEVER SWITCH BACK!!! For what ever reason and like I said I'm not a GURU but he said it has some kind of bad effect on the engine parts by switching from mineral to synthetic back to mineral. Maybe it's nothing but I just remember that very clearly and so please let us know if there's any major problems as a result of this Ok?
Thanks Bud and Good Luck.

 

Had a similar situation happen to my Prelude. I switched to synthetic at about 100,000 miles and within 500 miles it began to smoke, mostly when I started it. I switched back to regular oil but the damage had already been done. I finally ended up seling it. I will never put synthetic in any high milelage vehicle again.

 

Mine was doing the same but my engine was rebuilt and I thought I would be good to go after running dino oil for 2500 miles. I put synthetic in mine and it started to do the same thing.
I added a quart of lucas synthetic oil additive to mine so far the leak has stopped and the level has remained the same.
I think you can run a blended oil but you can't go back to dyno oil completely because of the seals.

 

What syn oil did you use (brand and 5W-30 or something else?)?

You might also try some of the high mileage oils if needed, they are supposed to have additives to swell up the seals again.

I have an 2003 4Runner and went to Mobil1 5-30, but noticed it states for new vehicles on the container. I'm happy with mine.


Maybe check bobistheoilguy for any info on your problem.

 

I switched my '97 to syn oil at 84k and now I have 96k and a year later no problems and I really don't expect any.

 

I switched over right about 100k...I'm at 116k now...and no headaches, no leaks, no funny stuff to complain about.

I wonder if this is just a prob with 2nd gens? Didn't they have something funky with the head gaskets as a recall?

Å

 

thats an old wives tale....switching from din to syn then back to dino will have the same affect as you using exxon gas this week and citgo gas next week....

in this case the only bad effect was the switch to syn in the first place. Now that its leaking its will probably continue to leak even with dino.

I switch to syn in my 92 Ford Ranger when it had around 150,000 miles on it....no leaks and no smoke....it drove perfectly to 250,000 when I sold it. I think I was lucky though, I had an S-10 after that and I switched to syn when it had 3000 miles on it and I had 2 leaks with only 3000 miles! Of course it was fixed under warrenty.

 

Just put in Synthetic Blend...its the best of both worlds. *S*

 

I made the switch @ 95K after using Auto-Rx for the prescribed process of cleaning and rinsing. I used Mobil1 10-30 and its been about 1K since it went in with no noticeable bad effects. As a matter of fact things are smoother and a bit quieter now with the synthetic oil and I even noticed a small increase in MPG too.

I am keeping an eye on things because of stories like yours but I don't think I will have any issues since the Auto-Rx seems to have really cleaned/conditioned the internals of the engine before I switched. I think that makes a difference and I am glad I found and followed the advice of the forum before switching to synthetics.

I have done a full synthetic swap in the running gear to Mobil1 and am very pleased with my results.

 

I bought the taco last november with 127k. at 129 I switched to Amsoil 5w30 (did the engine flush and all). I'm now at 160K (yeah, I drive alot), having just done my 25k oil change (I also did the recomended filter change at 12.5k. All of that said, I've had no leaks thus far, and I would consider my engine to be high mileage. I probably know the least of anyone on here, but I've gotta go with the guys who say get new gaskets.....

 

I was using Castrol Syntec 5W-50. I put Castrol GTX high mileage 10W-40 in it last night. The rear main seal is where all the leaking is taking place. I've heard it is a real PITA to change the gasket there. It only leaked when I was pushing the engine really hard.

I think I will take it for a drive up a long steep grade today or tomorrow to see if it's still leaking. I'll keep you all posted.

 

couldnt have said it better.

 

I believe I read something here at Yotatech about dino oil swelling the seals more than synthetic does? So when you switch to synthetic the seals don't swell as much thus allowing the leaks in the seals to expose themselves and letting synthetic through.

True or not?

 

I switched to synthetic about 10k ago. No problems for me so far.