Old enough to know better
Join Date: Dec 2006
Location: Beacon, NY
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Re: How to do compression check?
They actually only tell you anything if done on a schedule with the data trended on a graph. All engines have wear metal present in the oil. The presents of wear metal means the engine works. The oil analysis only shows you the rate of deterioration if you have multiple points of reference over time.(like at scheduled oil changes) 10, 20, or 30 % increase in wear metal in a three months scheduled oil change is normal.... 100% increase in the same amount of time is bad.
They can tell you if something is out of wrack. Blackstone has a pre-purchase test kit (includes a pump to get oil out) and will give results same day they receive the sample. I agree it is not as good as a trend, but it could find coolant from a small leak in the head gasket, the most common issue. It will show very high levels of metals if there is a bad bearing. It can also indicate if the oil has not been changed in a long time. There is a lot of info in there. I have no interest in Blackstone, but have used there services in the past and found it to be useful information.