Hi @gte343z , although I don't have any compression numbers, my oil consumption is about in the neighborhood that you are reporting. I have a 1991 HDJ81 (1-HDT) with about 203k kms on it. We bought it with 132k kms on it back in Nov. of 2016. Anyway, I first noticed oil dripping from the air supply pipe elbow pre-turbo, but post air filter, and soon thereafter fitted a Provent 200 catch can. I was catching oil in the catch can, but was not collecting the amount that I was consuming (in other words, what I drained from the catch can catch was nowhere near what I was having to replace.) Oil consumption seemed to be accelerated when I traveled at highway speeds (100 km/h to 110 km/h).
Anyway, you can check out the following thread (see another blow by question ) and see what I've been looking into. Just yesterday I vented my PCV to the open air (i.e. atmosphere), so it remains to be seen if my oil consumption decreases or not. @dan1554 and others were very helpful, proposing the idea that as the Provent 200's filter gets saturated with oil, it can be restrictive and actually cause a roadblock for the PCV gases, which would explain why venting to atmosphere may help in this case...
For what it's worth, I've noticed that my oil consumption varies...sometimes after a long road trip it'll be down by as much as a quart, and sometimes it won't even move. One thing that I've noticed is that these motors are notoriously difficult to get an accurate, repeatable oil level. I always let the engine cool and try to make sure it is absolutely level before I check the dipstick to compare apples to apples, so to speak. I swear oil must hide in nooks and crannies in this engine, because it takes me several tries to get the oil level just right after I change my oil...who knows.
Hope this helps you out!
Anyway, you can check out the following thread (see another blow by question ) and see what I've been looking into. Just yesterday I vented my PCV to the open air (i.e. atmosphere), so it remains to be seen if my oil consumption decreases or not. @dan1554 and others were very helpful, proposing the idea that as the Provent 200's filter gets saturated with oil, it can be restrictive and actually cause a roadblock for the PCV gases, which would explain why venting to atmosphere may help in this case...
For what it's worth, I've noticed that my oil consumption varies...sometimes after a long road trip it'll be down by as much as a quart, and sometimes it won't even move. One thing that I've noticed is that these motors are notoriously difficult to get an accurate, repeatable oil level. I always let the engine cool and try to make sure it is absolutely level before I check the dipstick to compare apples to apples, so to speak. I swear oil must hide in nooks and crannies in this engine, because it takes me several tries to get the oil level just right after I change my oil...who knows.
Hope this helps you out!
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