HM oil benefits if seals are new on old engine?

[nobb]

My 4Runner with the 3.4L 5VZFE just hit 350,000 kms. I picked this up 3 years ago with 300,000 kms and have been running Pennzoil Platinum 5W30 ever since. It does not use any noticeable oil between 8000 km OCIs. In this time, I've done ALOT of work to the truck just to bring everything up to spec maintenance wise. Engine wise, I've replaced the rear main, crankshaft, and camshaft seals as preventative maintenance (when I did the timing belt + clutch). This summer, I'll be doing the valve cover gaskets. The only other engine seals I can think of that are left are the oil pump + oil pan, but those are not known to be problematic so I probably won't go out of my way to replace those unless a problem arises.

So since 80% of the rubber seals on my old engine are new, is there still any value in using high mileage oils? From my understanding, high mileage oil's primary benefits are for softening old rubber seals. I've posted a UOA here a while ago and the conclusion was the engine was still in very good condition.

 

[Ihatetochangeoil]

My two cents is that the question is rhetorical. If you've got the mechanical savvy to replace the seals, I think you know the answer to your question and I agree with you. But then again, we all know the value of opinions...

FWIW, my 2004 Impala has 185XXX miles on it, leaks and burns NOTHING, and I'm not using HM oil in it, nor do I plan to. I use Amsoil 5W30, but any oil that meets specs and lets you sleep at night is OK.

 

[nobb]

I guess I am less concerned about the seals and more so about other areas of the internals and if HM oils offer benefits in that regards (Eg. wear)? I know QS Defy used to be high in ZDDP, but not anymore.

 

[FlyNavyP3]

I would counter that the most stressful job for a seal in your engine is the valve seal. They operate at the highest temperatures and are the most difficult to change. Running a high mileage oil may or may not help but I doubt it would hurt. The way I look at it if it can possible have a benefit with no risk, why not use it.

That being said, my 4Runner has 326,400 miles on it, consumes no oil and doesn't leak. Rear main seal is original as well. I don't run HM oil.

 

[pacc]

Don't the HM oils protect the seals by slowly destroying them? That's always kept me away from an HM oil.

 

[kschachn]

Originally Posted By: pacc
Don't the HM oils protect the seals by slowly destroying them?


No.

 

[SHOZ]

My Accent has burned oil since day one. Switching to synthetic slowed it down to 1 quart every 7k miles or so. Last oil change I went to M1 5w20HM and the oil use was cut in half over 7k miles. I'm about to change oil again and will go to M1 5w30 HM and see if it is really that much improved. Currently at 147k miles on the odo.

 

[Ihatetochangeoil]

Originally Posted By: FlyNavyP3
I would counter that the most stressful job for a seal in your engine is the valve seal. They operate at the highest temperatures and are the most difficult to change. Running a high mileage oil may or may not help but I doubt it would hurt. The way I look at it if it can possible have a benefit with no risk, why not use it.

That being said, my 4Runner has 326,400 miles on it, consumes no oil and doesn't leak. Rear main seal is original as well. I don't run HM oil.


Agreed with everything you've said. With 326K miles on it and condition stated, keep doing whatever you've been doing, it's obviously effective. You certainly don't need advice. Change the valve seals when/if you need to. Good job so far!! My two more cents is if it ain't broke, don't fix it.

 

[jorton]

Originally Posted By: pacc
Don't the HM oils protect the seals by slowly destroying them? That's always kept me away from an HM oil.

That would be a good reason.

 

[CT8]

All oils have seal "swell or conditioners". If the oils specs seem to work for you use them. Will your engine last another 350,000KM? lets hope so.

 

[SZR48207]

I've never seen it explained but my understanding is the "old school" way to soften seals was to make them swell up and degrade, so they wouldn't leak but wouldn't have much life left.

I guess the new way to condition them makes them softer without them swelling and degrading?

 

[OneEyeJack]

I'm having difficulty with the definition of "high mileage". The bottle states, 75K. I'm driving a 2003 4Runner with a just posted UOA here at 160K and everything is working great and in a 10K OCI it burns less that half a quart and sometime, nothing I can measure accurately. I would never consider changing from the oil that got me here because evidently my 2UZ-FE V8 engine has yet to enter the high mileage zone. 75K might have been high mileage 50 years ago but not today if given reasonable conditions, adequate maintenance and modern engine oil.

 

[Olas]

It won't do any harm to the 80% of new stuff, might help the 20% of old stuff. Valve stem seals are probably the next thing to look at.
IIRC a member on here contacted valvoline who stated it was perfectly ok to use maxlife in a brand new vehicle, so there shouldn't be any issue using a HM oil with new seals. I did the same with no issues.

 

[901Memphis]

It's preventative maintenance to use a high mileage oil. And defy still has more zddp than a lot of products.

 

[Kuato]

No value, but no harm either.

 

[Kuato]

Originally Posted By: OneEyeJack
I'm having difficulty with the definition of "high mileage". The bottle states, 75K. I'm driving a 2003 4Runner with a just posted UOA here at 160K and everything is working great and in a 10K OCI it burns less that half a quart and sometime, nothing I can measure accurately. I would never consider changing from the oil that got me here because evidently my 2UZ-FE V8 engine has yet to enter the high mileage zone. 75K might have been high mileage 50 years ago but not today if given reasonable conditions, adequate maintenance and modern engine oil.