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John918 · 06-08-2023, 08:19 PM

I am curious on how much fluid analysis tell you about the Coach, I understand that it will be able to tell you a lot about health of the engine, transmission, radiator etc.
The question is how many problems will the fluid analysis miss? in a another word, if the fluid analysis is perfect (of course it is a very good sign), does it guarantee engine, transmission etc. will be OK? or will there still be some problems that the fluid analysis could not detect?

The reason I am asking is the seller lost a lots of service records and he serviced the motorhome in different 3rd party auto shops (full time RVer), so there is no way to get those records back. Short of service records, is it too risky to buy even the fluid analysis is OK?

Please advise.
Thanks

jacwjames · 06-09-2023, 06:56 AM

I'm a believer in oil/coolant analysis but the bottom line is there is no guarantee that it will catch every thing before a failure.

There are some engines that have problems, wrist pin failure, EGR valve failure, timing gear pin failure.

Engine oil analysis, to be useful, needs to be done on a regular basis. When I was involved in maintenance at a large mining complex the engine was changed every 200 hours, which on newer heavily used equipment would be ~12 days. Oil sample and analysis was done every oil change. The company doing the analysis had these on file and would track the wear components and red flag anything out of spec.

Taking one oil sample is only a snap shot in time. ONLY if there is something really off will it be flagged. Better then nothing but not a magic bullet.

**Camp CA** · 06-09-2023, 08:21 AM

Treat it like a boat.....have a comprehensive engine survey completed by a certified motorhome engine inspector/shop as a condition of sale. Engine fluid analysis is only one component of that survey.

jacwjames · 06-09-2023, 08:55 AM

If the seller will let you it would be a good idea to drive it to a shop and have them hook up the engine to the computer. It would list any type of faults that may have logged.

Gary RVRoamer · 06-09-2023, 12:21 PM

I'll get sacrilegious here and opine that a single analysis isn't good at all about spotting problems. It would have to be something egregious, like water in the oil or oil in the engine coolant. Otherwise, it mostly finds potential clues, like traces of metals that might mean extra wear has been occurring. Even then, it might just mean the filters haven't been changed recently. And it can spot a change in detergents or viscosity, indicating its time to change the oil. That's handy if you are extending the standard change intervals.

The greatest value of an oil or coolant analysis is watching the trends over time, which means doing periodic analysis an comparing results. That tells you if your engine & cooling system is purring along happily or heading towards some unknown problem.

RoadTrip2084 · 06-09-2023, 12:25 PM

Quote:

Originally Posted by Gary RVRoamer

I'll get sacrilegious here and opine that a single analysis isn't good at all about spotting problems. It would have to be something egregious, like water in the oil or oil in the engine coolant. Otherwise, it mostly finds potential clues, like traces of metals that might mean extra wear has been occurring. Even then, it might just mean the filters haven't been changed recently. And it can spot a change in detergents or viscosity, indicating its time to change the oil. That's handy if you are extending the standard change intervals.

The greatest value of an oil or coolant analysis is watching the trends over time, which means doing periodic analysis an comparing results. That tells you if your engine & cooling system is purring along happily or heading towards some unknown problem.

Well sure, but finding the egregious stuff is pretty valuable when making a purchase decision. And finding anything of note might be enough to warn you off the coach. Worth doing IMHO for sure.