# Should high mileage oil be used in an engine if it's not using oil?



## sofsport (Jan 19, 2014)

High mileage oil contains additional seal conditioners.

Could they cause a seal to expand a bit more than normal?

If a seal is healthy enough to prevent leaks but is then crowded against its shaft, could it wear more and thus cause an engine to become dependent on the use of high mileage oil? 

When the seals do eventually need a little help to take up the slack, could they have already have expanded and worn away, if high mileage oil is used before it's necessary?

I am not an oil expert and don't know if that's how it works.


----------



## tagsvags (Nov 25, 2005)

If I was you I'd continue to use the proper VW approved oil...
If it ain't broke just leave well enough alone.


----------



## sofsport (Jan 19, 2014)

I use a heavier grade in the summer because I have a lot of short trips and because if the engine can safely pump 5w in all weather then it can probably pump 10 or 15 weight oil in the spring, summer and fall, without the pump cavitating or the oil filter bursting or leaking. 

The EPA made them stop putting so much ZDDP in oil but these engines still have flat tappets. That's the biggest potential problem I see. Who wants to have to put a new camshaft in an old engine just to get a few more thousand miles out of it?


----------



## Fogcat (Apr 29, 2015)

Is it proper VW/AUDI spec? THAT should be your concern, after that is whatever you choose. For me; that leaves little choice and my engine seems to like the proper oil anyway. Sludge is a concern as well. Proper change intervals and proper PCV operation makes a difference.


----------



## sofsport (Jan 19, 2014)

I am using Mobil1 15W50. I am guessing that they would not bother to certify the wrong grade with VW but it is still probably good enough on all counts, and is an SN rated oil. 

I always go back to Mobil1 0W40 when it's time to put the winter tires on.

The 15W-50 grade says it has a little extra zddp but it is easier to have a shop weld in a catalytic converter than to take the engine apart to install a new camshaft.

If working on the suspension and engine mounts is any clue, the engine is probably full of torque-to-yield bolts that cannot be reused, so cam, lifters, assembly lube, bolts, gaskets, G13 coolant, and the risk of getting grit inside the engine is the price of flattening a lobe. 

Or what if you wore through a cam follower? I have seen pictures online. It sure seems like the camshaft would want to stop and possibly break the timing belt which of course means major engine damage. 

I think even people who are not penny pinchers could use a 10W40 or a 15W40 in the warm months, except that the 15W40 oils are for diesel trucks and have additional zddp which may harm the catalyst, especially the 2.0s which had the oil consumption issues in the early 2000s. Why not? It may prevent some cold startup wear which would keep a car running better longer.

My warmups always involve low RPM driving until the temp gauge starts to register but for some, thicker oil may present a risk of draining the oil pan if the engine is subjected to high RPM running before it's warm because the thicker oil doesn't drain back to the oil pump pickup so fast. Something many people don't understand is that even a 0W40 oil is thicker when cold than at operating temp. 

Zero doesn't mean it's thinner than when it warms up, it's just thinner than it would be if it was 40W40. The viscosity charts show it's thinner and anyone who ever changed their oil with a warm car in order to not let the crud settle, knows it's thinner when warm than cold. It sounds like water when it splashes into the drain pan.

You can't say "thinner than 40weight" because technically a straight 40 weight is only rated at 200 degrees, so technically it could be all over the map.


----------



## sofsport (Jan 19, 2014)

tagsvags said:


> If I was you I'd continue to use the proper VW approved oil...
> If it ain't broke just leave well enough alone.


It is not breakage, of course, but wear which concerns me.


----------



## rommeldawg (May 25, 2009)

it would probably help to know year and engine of car you are talking about. i think it is neglecting service that causes the seals to get hard and leak. age will eventually cause this too but the newer seal material either in the old style or the newer ptfe seals is getting better and better and we have seen >200k without any leaking


----------



## sofsport (Jan 19, 2014)

rommeldawg said:


> it would probably help to know year and engine of car you are talking about. i think it is neglecting service that causes the seals to get hard and leak. age will eventually cause this too but the newer seal material either in the old style or the newer ptfe seals is getting better and better and we have seen >200k without any leaking


The make and model of my car is unimportant to the concept of whether high mileage oil might cause additional seal wear if it was put in to a car before it was leaking.


----------

