High milage oil

Joined
May 6, 2020
Messages
61
Location
Washington
We've all heard high milage oil has seal/gasket conditioner (whatever that is), more additives, blah blah. Sounds like a load of marketing garbage to me. Ive also heard once you use it, you should keep using it or risk leaky seals. What do yall think? Is it worth it or is it a load of bull?
 
Valvoline has a 300k guarantee on their HM synthetic and is API certified so I have no fears running it when on sale and regular Synthetic afterwards if on sale. Valvoline even states this as well as you can use when new.
 
Valvoline has a 300k guarantee on their HM synthetic and is API certified so I have no fears running it when on sale and regular Synthetic afterwards if on sale. Valvoline even states this as well as you can use when new.

I respectfully suggest you go read that "warranty" with all the conditions and exclusions. Its literally worthless and would cost more to sue to enforce it than the value.

Just find one person who has actually successfully used it ( and verify the claim isn't a staged baiter just to say there is one)

Then we will see just how much these warranties are actually worth.
 
I feel the same as ABN CBTE NGT. M1 EP "guaranteed" for 20k OCI. Good luck to anyone attempting to get that claim honored! The vast majority of these claims are so difficult to substantiate. I use M1 as my example as I'm a fanboy but realistic about the "warranty" and "guarantee" statements.
 
I read and understand the warranty. Just stayed there engine guarantee and it includes HM. I even have emailed them and they claim what I say. HM is safe and you can switch back and forth.
 
I read and understand the warranty. Just stayed there engine guarantee and it includes HM. I even have emailed them and they claim what I say. HM is safe and you can switch back and forth.

Yes and I've done it several times with no ill affects. But why would I buy HM oil you ask. Because with the sale and rebait it came to $4 a Jug. In fact I used in the previous OCI to what I have in the Toyota now. My car didn't even spontaneously combust.
 
My Sorento has seen all manner of HM, Synth Blend, and Conventional oils (full synth doesn't make sense in my application) and at 143,000 miles the engine doesn't leak at all, and if the engine uses any oil during a 5-7k mile OCI it's so little as to not be detectable.

Use what you want as long as the oil and filter get changed out, it will be fine.

In fact, at least when I have Firestone do an oil change, HM is the "cheaper" way to back into a synthetic blend, apparently at a Valvoline Instant place, asking for Synth Blend means you get their HM stuff.
 
Did you try searching the forum? I don't think we need to do the same topic more than a half dozen times, yet we probably already have.
 
Moved back and forth and used high mileage on new cars. No problems. IIRC WalMart's high mileage oil change is also the same as their semi syn. Both are ST high mileage synthetic. Notice that Wally's centers are back open so if this is still the practice it'll probably be my next change now that I'm running out of $10 Valvoline oil change coupons.
 
I think HM oil and their seal conditioners only work to the extent that if you always use it well before any leak starts, it might increase the life of moulded rubber and silicone gaskets. If you got old rock-hard valve cover gaskets that are leaking oil onto the exhaust manifold(s), it will never soften the gaskets and stop the leak. It could only reduce the leak slightly if you are lucky.

Old RTV gasket from the factory is futile to condition. It stays soft for a really long time anyway compared to moulded gaskets, but it still deteriorates overtime from being exposed to hot oil and its additives.

To conclude, HM oil is good for moulded gaskets before they begin leaking (and you gotta keep using it), or an attempt to stop slight seepage and keep using it. You can stop using it once you replace a bad gasket. Don't use it when oil is dripping.
 
I think HM oil and their seal conditioners only work to the extent that if you always use it well before any leak starts, it might increase the life of moulded rubber and silicone gaskets.

How do you know HM oil works and preserves gaskets if it never leaked?
 
How do you know HM oil works and preserves gaskets if it never leaked?
I just theorized that if you consistently use HM oil to condition moulded gaskets that are still good, it should help prolong the life of those gaskets before they eventually do leak as compared to a non-HM oil.

I do have a 20 year Tacoma V6 that I began using HM oil at 100,000 miles. It had no oil leaks at the time about 5 years ago. 40k later and several HM oil changes in, its original valve cover gaskets are still not leaking. That's something I've never seen before for something this old, and this truck drives around the desert where engine temps get even hotter. I really wanna say that the HM oil is working. Usually Toyotas leak oil like mad through valve cover gaskets
 
Back
Top