high mileage oil?

[KnightofNi]

this is actually for my g/fs car.

her friend told her that once you put in "high mileage" oil that you cna't go back to normal oil.

has anyone ever heard of this? can you offer actual evidence of it being bad, and what's so bad about it?

her engine is currently looking pretty dry both for oil and coolant. i only have regular 10w-40 and she's worried that i will mess up her engine.

[ducpainter]

this is actually for my g/fs car.

her friend told her that once you put in "high mileage" oil that you cna't go back to normal oil.

has anyone ever heard of this? can you offer actual evidence of it being bad, and what's so bad about it?

her engine is currently looking pretty dry both for oil and coolant. i only have regular 10w-40 and she's worried that i will mess up her engine.

Sounds like BS to me.

[KnightofNi]

Sounds like BS to me.

that's what i said, but her friend worked for auto zone for a long time...

i have just been tinkering with engines for a few years and listening to the oil chatter on various forums.

[ducpainter]

that's what i said, but her friend worked for auto zone for a long time...

i have just been tinkering with engines for a few years and listening to the oil chatter on various forums.

I think the whole high mileage oil thing is a gaff.

What does it have?

More detergent?

[KnightofNi]

I think the whole high mileage oil thing is a gaff.

What does it have?

More detergent?

supposedly it has additives to recondition seals.
it seems from my brief examination tonight that they are at least semi-synthetic if not full syn.

[ducpainter]

supposedly it has additives to recondition seals.
it seems from my brief examination tonight that they are at least semi-synthetic if not full syn.

I'm not buying.

[KnightofNi]

I'm not buying.

i'll buy that syn is at least somewhat better at protecting the metal on metal parts than conventional, but the rest of it i'm not so sure about either.

then again, there are tons of testimonials out there on several diff sites.

[Speeddog]

Howie to the white courtesy phone please. 

Just for fun, what kinda car, how many miles on it?

AFAIK, by law, all motor oils sold for cars can be mixed with no dire effects.
But that may have been BS I was hearing. 
Howie would know.

[Langanobob]

If by "high mileage oil" you mean that stuff at Walmart that's labeled for cars with lots of miles on them, it's just a marketing scam and it's no different than "regular" oil.  It won't hurt an engine to go back to regular oil because it is regular oil.

If by "high mileage oil" you mean synthetic oil like Amsoil that's marketed that it will last for lots of miles between changes, it doesn't hurt to go back to regular oil.

Tell your gf that I said her friend is an idiot.   

The danger here is that if something does happen to go wrong with your gf's car after you change the oil, it will be your fault.

[hooligan machinist]

The danger here is that if something does happen to go wrong with your gf's car after you change the oil, it will be your fault.

Even if it's only a muffler bearing 10 years later, and especially if you're married to her by then.

[madderdaddy]

I don't fall for the high mileage oils. I have ran cars past 300,000 miles on regular 10-40, 10-30 with no problems.
Now if you are switching back and forth from synthetic to regular oil this could cause a problem. I don't know about effecting the engine but i do know that regular oil naturally tends to gum up and will stop up pores worn in your hoses and so on (when cars are older of coarse)... When you go to synthetic, it tends to not gum up and will seep through the pores in the older hoses. so you end up with oil leaks and don't know why. anyways long story short high mileage oil cost more, regular oil works fine and will do its job just as well as high mileage oil, and synthetic is best.

[KnightofNi]

Howie to the white courtesy phone please. 

Just for fun, what kinda car, how many miles on it?

AFAIK, by law, all motor oils sold for cars can be mixed with no dire effects.
But that may have been BS I was hearing. 
Howie would know.

haha, he was the first one i thought of. i already PMed him.

If by "high mileage oil" you mean that stuff at Walmart that's labeled for cars with lots of miles on them, it's just a marketing scam and it's no different than "regular" oil.  It won't hurt an engine to go back to regular oil because it is regular oil.

If by "high mileage oil" you mean synthetic oil like Amsoil that's marketed that it will last for lots of miles between changes, it doesn't hurt to go back to regular oil.

Tell your gf that I said her friend is an idiot.  

The danger here is that if something does happen to go wrong with your gf's car after you change the oil, it will be your fault.

you should have heard the convo last night 

[Howie]

All most of us know for sure about motor oil for our car is what is on the top of the can.  
From the top of the can you can tell the following:
 Oil weight.  
 If the oil is energy conserving or not.
 API for gasoline and diesel plus, if included, ACEA European ratings.
 OEM manufacturer's approvals.
 Whether the oil is fully synthetic, a blend or not (maybe, since you, well, I've never seen on the can if the oil is  
     group 3,4 or 5).  Group 3 is a blend, 4 and 5 pure synthetics.

There is tons of good information on oil ratings on the interwebs.

Even most of the scientific oil testing you read is not valid new product and reformulating of old product has taken place to meet new standards since the article has been published.  
For the most part, the only people who really know more than this are engineers inside the petroleum industry like our dear departed friend George (we miss you),  and people who tear down identical engines under heavy usage such as a taxi fleet or a race team, but that information may not translate to our daily runner.  It is possible some oils may have additive packages, but more than likely just marketing.  Either way, you will not know for sure.  

Switching back and forth between oils should cause no problems.  All motor oils are supposed to be compatible.  You may see more seepage if you switch to synthetic oil on an older car due to the molecular structure of the oil.  I forget, either PAG or Ester oils can do this.  If so, just switch back.

Bottom line is any good oil of the proper weight and rating for your high mileage car should work just fine if changed frequently enough.  

This rather long reply is due to a request from a board member.  Blame him   I see the member just revealed himself.

[KnightofNi]

thanks howie!

we actually just took her car in and i regret to inform everyone that i was overrulled.
it has nothing to do with the fact that the guy wants to sell a higher priced product that he told her that she shouldn't put conventional oil back in
ohh and apparently anything over 75K miles is high mileage and has to use the high mileage oil.



this reaffirms my hatred of mechanics and makes me wish i had just gone to mechanics school so i could either do it myself or at least diagnose the problem and treat them the same way they treat me.

i swear to god the guy seemed totally disinterested in actually diagnosing the problem, but he knew she needs high mileage oil as well as a coolant flush (which was done at 140K) i asked him to check the thermostat and he said "well i don't know if that's bad or not." no shit, that's why i'm asking you guys, the mechanics who supposedly would have the equipment to do such a thing, to test it.


ohh and speeddog
it's an 02 honda civic ex with 168,750 miles on it.
it's been very well maintained and as far as i can remember hasn't had any problem more major than a flat tire or dead battery until now.

[Langanobob]

i swear to god the guy seemed totally disinterested in actually diagnosing the problem...

I don't think you mentioned that it had a problem?  What is it?  What kind of shop was this?  My wife had a Honda Civic that was a great car but at just about 170,000 miles the water pump conked out. 

At least the "high mileage" oil won't do any harm. 

I've completely failed in efforts to find a competent repair shop.  Even tried dealers and high end type places.  They all seem to be idiots or crooks or both.  The notable exception is a place called D&D Transmissions in Reno, NV who have successfully rebuilt two transmissions for me.  I mention them out of fairness since I did find at least one good shop.