Changing Oil Type To Fix Seal Leaks?

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Steve_Sr

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Hello,

Has anyone seen or know of situations in which changing oil type (i.e from full synthetic to dino) has had a beneficial effect on main or valve stem seal leaks and lowered oil consumption?

One reason that I am asking is that this situation occurs if using a full synthetic oil and then doing an Auto-RX treatment which requires switching back to dino for the treatment and the rinse phase. So if the leak is stopped is it because of the Auto-RX or is it because of switching oil chemistries?

Thanks,

Steve
 
Assuming ARX works as advertised, it would be removing deposits that had formed near the seals, resulting in some leakage. If the seals were otherwise in good condition, once they were reconditioned by fresh oil then the leaks should close up.

IMO just the switch from syn to dino wouldn't stop leaks on its own, unless maybe it was a HM dino.
 
Last edited:
YMMV but I have had good luck with high mileage oils in older engines, they do seem to swell up the seals and help with leaks after extended use, 20k-30k.
 
Originally Posted By: crazyoildude
what vehicle and engine??


Toyota 1MZ-FE (3.0 V6) 240K miles. Run entirely on Amsoil full synthetic since break-in.
 
use 5w30 pennzoil high mileage and by the second change it should be stopped or slowed down unless its from the oil sender.
I use that in my old engines and have had great success.
 
I know everybody thinks of it being a myth, but a motor will occasionally weep oil if switched from conventional to synthetic.
 
The few valve stem seals I have seen that leaked were cracked and falling apart.

Valve stem seal leaking = blue smoke at startup. Crankshaft seal leaking = oil drips on pavement.
 
Originally Posted By: Gabe
I know everybody thinks of it being a myth, but a motor will occasionally weep oil if switched from conventional to synthetic.

It wasn't necessarily a myth, but way overblown.

It wasn't due to detergency or cleaning out seals, but that PAO has a tendency to harden seals and a finished motor oil uses a seal softener to compensate. They could sometimes leak before the seal softeners took effect.

Also, this effect is usually in older engines where the seals are marginal and ready to leak with anything that messes with the balance. Never happens with any engine with decent seals.
 
I had a small leak on my Ranger running QSUD. I switched to Pennzoil HM 10w30 and the leak stopped within 1,000 miles. Doesn't mark it's parking spot anymore.
 
hm oil can repair a seal I was not always a believer but for the last 5 years i have seen a lot of leaks slow down or stop completely with hm oils

I have been in the engine business a long time and i know hm oil can help in a lot of cases.
 
Originally Posted By: Norm Olt
OK I'll bite: what's the difference between

LUBRO-MOLY & LIQUI-MOLY Oil Savers?

Cheers!


The short answer: Lubro Moly is an MoS2 additive. Motor Oil Saver thickens oil, and has additives to condition seals to help stop leaks. I haven't used the oil saver but heard only good things about it. Torn seals, or very bad leaks will require repair.
 
Originally Posted By: bvance554
If its already leaking you have a bad seal. No oil will repair a seal.

Not necessarily true, my '93 Grand Marquis had a slight drip from the rear main and HM oil cured it completely...

What you guys don't seem to get is to start using the HM oil at around 100K mi and you'll probably never have a leak from worn/shrinking seals... It's PREVENTATIVE maintenance, not after the fact...
 
Originally Posted By: Brybo86
it has 240k and you already did auto rx? or you are thinking about it? how much oil does it consume right now?


No Auto-RX yet... I am just wondering whether to attribute any positive outcome to either Auto-RX or the change in chemistry from full synthetic to dino.
 
Originally Posted By: Donald
Valve stem seal leaking = blue smoke at startup. Crankshaft seal leaking = oil drips on pavement.


This is a rear main seal leak that appears to be getting worse. The front also starts seeping a little bit at the 100K mark but it gets changed with the timing belt
 
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