High Mileage Oil VS HDEO's

[GumbyJarvis]

I have used High Mileage oils on both my Personal vehicle, family vehicles, and friends vehicles. (QSHM w/S50 SM and QSHM SN stopped a small leak in my truck, PHM is currently holding up in dads leaky Saturn)

My first OC ever using a HDEO in a PC was a few weeks back, buddys van was killing oil, leaking burning, you name it, he got to the point of putting the cheapes 20w50 in it, and in a Chevy Lumina van, that is no bueno..

He was out of town, and his wife was at his brothers house (my other buddy lol) and the check oil light kept flashing, engine bogging etc told her I would do the OC cheap, if she took me to WM to grab the stuff. After long debates of QSDefy 10w30, or T5 10w30, I went with the T5.

So far so good, no burn, no leak. Im stumped.
I have no need really personally to want to know. Just as a general forum discussion and for the newbies here learning about Oil, what would you rather put in a car with a leaking/burning problem?

a HM PCMO or a HDEO?
Why?

Ive used both, with good success with the HM PCMO, and so far so good with the HDEO...

 

[Highline9]

If HDEO is good enough for trucks that run a million miles it's got to be better than pcmo.

 

[Garak]

Originally Posted By: GumbyJarvis
a HM PCMO or a HDEO?
Why?

Ive used both, with good success with the HM PCMO, and so far so good with the HDEO...


I, too, have used both. I suppose it depends partially on price and partially on what problem you're trying to address. The old F-150, before its rebuild, leaked like a sieve and had enormous fuel dilution problems such that a normal PCMO 5w-30 would cause the engine light to come on at idle when at operating temperatures in the summer.

I used MaxLife 5w-30 in the winter and Delvac 1300 15w-40 in the summer, and did that for a couple years or so. With both oils, the leaks slowed to the point I didn't have to add anything over the interval. The oil light didn't come on with either oil, although the used oil smelled horribly like gas.

In other high mileage type scenarios, both are acceptable, too. If one is looking for higher ZDDP, there are things like Defy and also HDEOs in 10w-30. Both an HDEO and a HM can be similarly priced, depending upon rollbacks, of course. The HM wins if you are looking for a grade like 5w-30 for winter use or year round use. If a 10w-30 is sufficient and you don't have huge seal issues, there's nothing wrong with HDEO.

 

[LeakySeals]

I've used T6 and M1 HM. The difference is thickness. Instead of swelling the seals with a thinner HM oil, your using an oil too thick to pass through the leak you have. Less flow at the rings, less consumption. Although its listed as the same grade HDEO's are as thick as they can be without changing the grade. HDEO applications are big diesels, so thinness is less of a requirement. You pay a wear price for oil that doesn't flow as well long term. But on an old vehicle/engine it may not matter.

 

[GumbyJarvis]

Originally Posted By: LeakySeals
You pay a wear price for oil that doesn't flow as well long term. But on an old vehicle/engine it may not matter.


Exactly! but chances are if youre debating betweem a HM oil or a HDEO the car in question isnt probably the best running thing in the world

 

[4x4chevydude]

I have done both and personally think that the engines run better on the HDEO when they are worn out. I think that once your engine gets to that point your not concerned with great flow or anything you just want it to run for a while longer and the HDEO stands up to that test. Especially on Hot summers or long trips

 

[Garak]

Originally Posted By: LeakySeals
Although its listed as the same grade HDEO's are as thick as they can be without changing the grade.


Bingo. For a 10w-30 HDEO, a HTHS of around 3.5 is the norm, rather than the exception.