not enough oil change = lost compression?

[OS]

I have a friend with a 95 accord or so with 100k miles. He took it to the mechanic recently and the mechanic says the car is losing compression. This seems odd since 100k miles isn't particularly high, but upon further digging, my friend has been following the normal/light use interval (7500 miles) for oil changes for the life of the car when IMO, the car needs severe (lots of city driving and short trips). Could this be the main cause of his problem?

 

[HappyPuppy]

It's doubtful. It could be due to a leak in his air intake allowing dust and dirt in, or he possibly overheated the engine at some point.

 

[GalvanizedYankee]

Originally posted by: HappyPuppy
It's doubtful. It could be due to a leak in his air intake allowing dust and dirt in, or he possibly overheated the engine at some point.

So very true. I've seen improperly installed air filters cut engine life in half. The ducting from the a/f housing to the intake manifold can have a leak. When I adjusted the valves on my nieces civic @ 97k, half of them had no clearance at all and that will kill compression.

 

[XZeroII]

Not performing regular oil changes will definately cause problems with a car. I don't know much, but I would say that crummy oil would break down and cause wear on the cylindar walls, thus less compression. ?

 

[The Stigenator]

my focus requires 5K oilchanges until 100K and then 3K after that.

so that's what im doing..

lower compression among all cylinders could mean something with the air intake..

lower compression in one.. you got bad rings.

 

[GalvanizedYankee]

Changing oil at 7.5k wont kill compression, the bearings will load up with contaminates and acids will form to raise general mayhem, like eating away at the bearings. Journal wear will result.

REMEMBER, the OP said SEVER use.

But with poor air filtration, this is what happens.

The bigger pieces of filth will get blown out as the engine is running but some will get trapped between the valves and seats, this will cause pitting and result in leakage of both intake and exhaust valves.

The smaller pieces of dirt .0008"- .0015" will lay on the intake valve stem and moving up & down will lap it's guide.

These same sized bits of crud will score the cylinder walls.

I've overhauled too many motors and the above is true.