5w40 in a 1985 corolla caused oil leak

[tadaima]

Well got this corolla and changed its oil to Shell Rotella 5w40 Synth (Group III), and the car is dripping oil, about 1/4qt a week.

Looking at the owner's old receipts I see that it used 20w50 for its life, guess i should drain and refill with 20w50.

So i guess this is just a statement saying that Synthetic oils do cause leak, well I guess in a sense that they are thinner and pass through spaces easier than a 20w50 oil.

 

[JohnBrowning]

This is a perfect time to try Auto-RX.

I once smoked a lite a cigar and as I did a car bomb went off near by. Did my Cigar trigger the car bomb or were the two unrelated?

THe car is 19 years old the seals are tired. Group III is not synthetic!! It had as much to do with the seal leak as my cigar did with the car bomb!

 

[tadaima]

John,

But how would Autorx save like the mainseal, it would just clean off more old deposits and leak faster right?

Which brings up another question, wouldnt we all want some sludge to keep the seals longer [plugged up]?

 

[GSV]

Sludge GOOD, Synthetic oil BAD!

Me want no leakey, never change oil no more....

 

[tadaima]

Not a lot of sludge, but if the engine and the area around the seals are sooo clean. Say 15-20yrs from now when they start to crack, there's nothing between the oil and seal.

But if there's a nice thin film of sludge or some grime, even with a seal that is slightly dry rotted or cracked, it could get away with without leaking.

Correct me if I'm wrong.

 

[tom slick]

what engine does it have?

 

[tadaima]

4ac 4cyl 1.6L carb

 

[GSV]

tadaima,

I apologize for being an A-hole. I'll blame it on being online too early in the am.

 

[outrun]

Leak in this case was a good thing.

My working assumption is that it found and eradicated sludge that decided to live on your seals/gaskets.

Now would be a good time to begin an Auto-RX cycle. Attacking the oil for actually doing its job is not fair.

 

[robnitro]

Try some 15w40 Heavy duty diesel oil like delvac, delo, or rotella. Rotella 15w40 helped my friend's old supra, after 10w30 and 5w30 was leaking from it a lot.
I'm not into 20w50, but hey, if the engine likes it...

 

[JohnBrowning]

tadiama, sludge is what damaged the seal. When sludge covers a seal or gasket it dries out and develops cracks. The cracks eventualy the cracks will cause the total failure of the seal or gasket! Sludge does not offer any of it's own strutural support. Sludge relys on the seals to support it like a parasite liveing on a host. THe sludge does nothing to help it's host out. When the structure of the seal fails then you get a leak. I doubt that a synthetic either full synthetic or group III could have worked quickly enough to cause the leak in the amount of time you had it in. More then likely the leak was getting ready to make itself known and the oil change just happened to take place before it happened. In other words even if you had but Chevron Supreme in it would still have developed the leak at the same time. THe oil you used is not even a true synthetic! Seal failure is a mechanical problem. It might have been cused by the chemical formation of sludge but the mode of failure is structual!

Auto-Rx will only help if the seal is not torn just hard and dirty. If the seal has a bunch of micro tear or a full blown tear then no chemical is going to fix it!

I would just replace the front and rear main seals and be done with it!

 

[tadaima]

Rob: Yea I think I'll put back the 20w50 since that's what it had over the last 10years.

Browning: THanks for the info, makes sense.