There are a couple of checks, which will give you a pretty good picture of the health
of your engine.
#1 A compression
bleed down check. It's like a compression
check, only each cylinder is pressurized & the time measured for how long it takes for the pressure to get down to X. Tells you the health of your piston rings, & valve train.
#2 A lube oil, & transmission
analysis. You get a small sample & send it off to the lab, where they check to see how much of various types of metals are in the fluid. And then basically compare these numbers to an engine/transmission wear rate chart. It's an inexpensive test, & tells you a lot about the health of several different major components in your engine or transmission
I got my Dad HOOKED on the above for his car. Gives him a Lot of peace of mind now that he's retiring... knowing he's got a solid vehicle.
So yeah, not a diesel
only, specific test.
I've got the company name around here somewhere, likely in my car, but if you do a Google
search, you'll come up with companies that'll do it for you. You just mail in a small sample, like 3oz or so.
Companies which run a lot of industrial equipment
& engines do the fluid analysis a lot. Especially as it can catch problems early, like say a bearing starting to go bad, or traces of fuel
in the lubricating oil.
Then, knock on wood, if it's a bolt on component, it can be swapped before the whole engine has a catastrophic failure.
Or if you're shopping
for something with an engine, & have 2-3 days to play with (literally), you can send out a sample on the vehicle in question. And with test results in hand, bargain from there. Yeah, the tests are quick, it's the mailing that's the long part.