Long Drains and Seal Life

[The Critic]

I've always wondered if performing long oil drains will have negative effects on the engine seals.

I was talking to AcuraTech the other day and he told me that nearly all of the rear main seal jobs that he does at the shop are a result of super long oil change intervals (12k+).

On my Saturn, I did 5-10k intervals on conventional oil despite the 3k recommendation for severe service. When I had to replace the valve cover gasket and spark plug tube seals at around 96k miles, the engine was sparkling clean, but the gaskets just crumbled when I removed them. Was that the result of a long oil change interval?

 

[DragRace]

The oil pools inside the valve cover as it slowly drips back inside the engine via "drain back holes" inside the cylinder head, then it cycles up to the valve train again. On a V-8 or V-6 engine, the valve covers are at an angle, and the oil accumulates at the bottom of the valve cover.

This causes the oil to accumulate in the valve cover longer and exert more pressure on the valve cover gaskets.

This is also why,I NEVER install cork gaskets when assembling an motor back together. I'll use steel reinforced gaskets,which are stronger and last longer then those POS cork gaskets.

 

[The Critic]

The engine is an in-line four and the OE gaskets were molded rubber, not cork. Still, the rubber gaskets flaked and crumbled when I tried to extract them from the cover, especially the spark plug tube seals.

 

[DragRace]

Rubber does not hold up to extreme pressure and temps either.It maybe an inline 4-cylinder,but same principle.

 

[Shannow]

Critic, I don't think that long drains do very much to shorten seal life.

Might be some free radical perroxidy thing happen, but I don't think that your crumbling valve cover gaskets are unique.

 

[INDYMAC]

The G35 VQ35DE spark plug tube seals don't discriminate about OCI lengths either. They're just junk. To compound the problem, you have to replace the valve cover just to correct the leak. Consider yourself fortunate by just having to replace the seals and gaskets.

 

[The Critic]

Originally Posted By: INDYMAC
The G35 VQ35DE spark plug tube seals don't discriminate about OCI lengths either. They're just junk. To compound the problem, you have to replace the valve cover just to correct the leak. Consider yourself fortunate by just having to replace the seals and gaskets.

Yup, I've seen quite a few of those as well.

I wonder if you could use RTV in place of the rubber seals on that particular cover. It would save a lot of money.

 

[Pablo]

I would say it's possible with overextended use of an inferior oil. But I don't think it's extended OCI's alone. I would have some serious leakers if that were the case.

 

[Gary Allan]

Old age ..heat fatigues everything ...sooner or later...

 

[Chris Meutsch]

Originally Posted By: Gary Allan
Old age ..heat fatigues everything ...sooner or later...


Sincerely,

George Hamilton

 

[DragRace]

Originally Posted By: Gary Allan
Old age ..heat fatigues everything ...sooner or later...


Thats what I'll stick too

 

[Pablo]

Read about seal conditioners (I think Mola had a post or two), and the chemistry involved. It's more than possible that some of the conditioners are breaking down in oils that aren't designed for long drains, or some oils that aren't designed for long drains have break down constituents which neutralize, or override the seal conditioners.

 

[oilboy123]

Good point.

 

[demarpaint]

Originally Posted By: Pablo
Read about seal conditioners (I think Mola had a post or two), and the chemistry involved. It's more than possible that some of the conditioners are breaking down in oils that aren't designed for long drains, or some oils that aren't designed for long drains have break down constituents which neutralize, or override the seal conditioners.


So then is it possible to have a good UOA, but have seal conditioners that are depleted and damage can occur to engine seals? If so, people running a conventional oil for say 7500 miles and getting what looks like a good report could still have problems with leaks etc. down the road?

Frank D

 

[PandaBear]

A $20 used oil analysis probably won't tell you much, but if you keep a safe OCI then it should be ok. I don't think running an oil designed for 10k to 10k would cause harm, but an oil that was 7.5k to 15k would be a problem.

 

[ToyotaNSaturn]

Isn't this the exact job for Auto-RX?