High mileage oil?

GTFTW · Sep 17, 2011

A friend of mine has a 2000 GT with leaking valve guides. It has been recommended that he use high mileage oil to at least remmedy the situation.

Will high mileage oil help at all? Also, our local auto parts stores dont carry high mileage oil in the recommended 5w20. What other weights can be use in these engines?

thanks

trinity_gt · Sep 17, 2011

High mileage oil is snake oil. Oil is oil. A slight variation in additive content will not mitigate oil migration past oil seals.

There are three things you can do/try:

mechanical: fix the valve seals and or guide problems
thicker oil: a 10W30 or 10W40 oil is thicker and may be less prone to getting past the seals than the water-like 5W20 "recommended"
seal conditioner: Automatic transmissions are packed with seals and when they act up, loss of hydraulic pressure around them can cause shifting issues; a bottle of "conditioner" can be added to transmission fluid to cause the seals to swell a bit to get a bit more life out of the trans. The seals used in engine valve guides may respond similarly to a bit of engine "stop leak" conditioner such as Lucas' "Engine Oil Stop Leak" poured in the sump

Noobz347 · Sep 17, 2011

trinity_gt said:
[*]seal conditioner: Automatic transmissions are packed with seals and when they act up, loss of hydraulic pressure around them can cause shifting issues; a bottle of "conditioner" can be added to transmission fluid to cause the seals to swell a bit to get a bit more life out of the trans. The seals used in engine valve guides may respond similarly to a bit of engine "stop leak" conditioner such as Lucas' "Engine Oil Stop Leak" poured in the sump
[/list]

Snake oil... Hmmmm... depends... The conditioner mentioned above is one of the additives in high mileage oil. It's designed to swell seals and also contains a coagulant (of sorts) to seal up small leaks that allow oil to pass through. They also contain additional detergents and primers that allow the coagulants to adhere to surfaces of these areas.

They are not designed to stop oil leaks like the ones that you might find in your driveway. Instead they will fill the microscopic variety and place polymers in those spots that give additional protection to those areas as well as additional lubrication.

Some can even, "target" specific wear areas by reacting differently to the heat range it is operating in. What I mean is, they break down differently dependent on heat releasing different by-products that are beneficial to a specific area of the engine (piston rings, piston skirt, viton valve seals, etc.).

It's not all hocus-pocus and some are better than others. They will NOT however, repair a damaged engine.

trombonedemon · Sep 17, 2011

Noobz347 said:
They will NOT however, repair a damaged engine.

W/that been said; maybe time for an engine rebuild. Upside though, time for some stronger parts?!

Deleted member 38176 · Sep 17, 2011

I've got leaking seals as well. I'll use a combination of HM oil and additives and see if that helps. Replacing the seals just isn't in my budget at this particular time

bhuff30 · Sep 17, 2011

Leaky valve seals isn't going to hurt anything. Just keep the oil topped off. Aside from a small and occasional puff of smoke on start up and take off from idle, you would never know.

Personally, I still run the good stuff (full synthetic) on my 194k mile engine and never put more than 2qts in between the 7k miles oil changes. Yes, my valve seals leak too, but it doesn't hurt anything.

Deleted member 38176 · Sep 18, 2011

bhuff30 said:
Leaky valve seals isn't going to hurt anything. Just keep the oil topped off. Aside from a small and occasional puff of smoke on start up and take off from idle, you would never know.

I guess I have a severe leak then because the puff of smoke on startup and take-off is pretty drastic and it smokes a little @ idle as well.

mr-mike · Sep 22, 2011

when I got up to 140,000 I switched to the Hi Milage oil & it seems better some very lite leaks are gone mileage is OK its cheaper & seems to keep it running perfect , it has some additives I still change every 3000 miles I'm up to 170000 & she dont smoke & gets good mpg its a 1999 had a few problems over the years but all & all the 4.6 is good solid motor I just rebuilt the whole brake system front brake hoses calipers the back was done a short time ago , the front hoses are important they do wear as there is alot of heat up there & also no more cheap brake pads ever ...top of the line Raybestos from now on .....................

sn95jones · Sep 22, 2011

I've always used Castrol GTX high mileage motor oil. Always worked great for me. I'm due for an oil change and I also have leaky valve seals. It doesn't burn that much oil but you can tell it does. Now that I'm due for an oil change I'll go for a heavier weight and some lucas stop leak stuff. I don't trust any of those other brands all they do is clog your motor.
I only trust Lucas and Seafoam when it comes to having issues with the motor. Its not a permanent fix but it will last long enough.

Noobz347 · Apr 5, 2020

London Kurt said:

Figures

That is as good of a source as the post you linked and I nuked.

I hope that you are here for questions because your replies are useless. Everybody by now, can google something and click on the top link. Try bookface. They love that sort of thing. Zero effort or understanding required. There, you can perpetuate the same misinformation until the internet says that it's true.

High mileage oil?

GTFTW

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