What oil ??

[wolf_walker]

Yeah, I don't imagine mixing oil brand or weight (within reason) would have too much in the way of negative effects. That poor ring seal you mentioned is the same thing as blow by, more or less.

I ran yz490's and a Maico 501 and various other old bikes, great fun. Nothing perfesional, but I covered many a mile on those things.

 

[JHL]

Hey Wolf,

No offence taken, as I said I still have my flame retardent coveralls and I expected more, all I can say rightly or wrongly is that how I have done it over the years. I have probably had over 100 cars pass through my hands from beater`s to a Porsch and as I said I`ve only had one engine blow up on me, a Buick which threw a rod, most likely due to excessive rpm rather than lack of oil.

The most important thing is to at least have some in the engine after that I don`t worry to much. I work for a company that has its own oil analysis lab, it deals mostly with locomotive companies but does the occasional car report, I wouldn`t waste money on that either although I can have it done for free.

J.

 

[cntrhub]

Yes, blow-by is caused by the compression blowing past the rings and into the crankcase. Warm up the engine and let everything expand to running temperature. Remove the oil filler cap. If it puffs smoke out the filler hole, you have what is termed, "Blow-by."
A better test for compression loss is using a, "Leak Down Tester." This is forced air through the spark plug hole, and the cylinder is on the compression storke. You can hear the air loss through 4 of the main sealing agents.
The intake valve will hiss out of intake manifold. The exhaust valve will leak from the exhaust system. The oil filter cap will vent air from the weak/worn rings. Lastly, if the head gasket is the culprit, using soapy water, swab a wet brush between the head and block will diagnose this air loss, forming bubbles at the specific cylinder(s).

 

[gary b.]

Let's take 5W30 & 10W30 for an example, the first numbers indicate the thickness of oil when cold. During cold engine start-up , a 5 W will flow faster than 10 W. When the engine is at normal operating temp., both oil's are the same !