I am trying to sell my fishing boat (also have offshore boat) that has a 96 Volvo 5.8FSI engine with 210 hours. I have serviced the boat as required, 50 hours oil or every year (whichever came first) and the boat starts flawlessly and runs perfect.
I have a buyer that I took out for a sea trial with the listing broker and the boat ran perfect. After the sea trial the buyer had his mechanic look over the engine and everything was fine until a few days later he says he is no longer interested because one of he cylinders has low compression (105 compared to 130). I figured either the mechanic got a bad reading or maybe one of the valves was sticking because the boat had not been run in fours months while it sat at the brokers.
I received a call today from the broker and he said the buyer had an oil analysis done and it said that the engine was in crytical condition and would need an overhaul. I have serviced this boat perfectly, even pulling the manifolds every two years to check for corrosion. The buyer is now interested in the boat again and willing to pay $4,000 more for it if I pay for the rest of a new long block (extra $2,500). I am already giving the boat away for less than what it is worth but also understand the market conditions right now. What I would like to know is if the oil analysis can really tell if the engine is that close to being a big book end? I have a hard time giving up the extra money for a boat that currently runs PERFECT. Can having a boat sit for that short period of time have that bad of an affect? Any input is appreciated!

Oil analysis can do a very good job, most of the time they can tell exactly what parts are wearing or braking down. Take a sample and have it done it only costs about $20.00 then you'll know for sure weather or not he's just trying to get a better deal. I use amsoil's oil analysys service and have been pretty happy with them.

The only accurate way of gleaning anything from an oil analysis is many of them at set intervals. You need history. Like an analysis every 50 hrs. When something changes is when you know you have a problem. I'd love to hear what they were basing their "The engine is in critical condition" on.

I send a sample of my twin turbo engine's oil to Blackstone Labs at every oil change. I've done so since the very first oil change after dyno testing it. As has been mentioned already, oil analysis is very good at identifying potential problems before they become mechanically appearant without a complete teardown and inspection. For instance, traces of copper or lead at increasing levels over time can be indicative of abnormal bearing wear. Silicon can indicate a blown headgasket, intake gasket, or cracked block, etc from coolant contamination. High levels of iron or aluminum can indicate excessive cylinder and piston wear. Gasoline in the oil can indicate worn rings or excessive piston to cylinder wall clearance. Combustion byproducts can indicate excessive blow-by.

While a one time sampling can be helpful, you really need to establish a baseline and trend before you can really accurately interpret the analysis readings. Most oil analysis companies will suggest a followup sampling when there is a reading out of the normal range.

With all that said, since you don't have a history of oil analysis reports to compare to and as a result you can't identify a trend, I'd keep in mind the results of a leak down test, oil pressure readings, etc.

Thanks for the responses. I think I'll start sending oil in for analysis on my Powerquest.