Synthetic Oil Change Frequency

[sailnow2011]

I have taken a diesel engine past 17,000 hours changing the oil every 800 hours.

[ArmyChief]

I think it is also worth mentioning that in the US....the word "synthetic" is DIFFERENT than overseas.

[Emerald Sea]

If your engine is under warranty, I would recommend that you religiously stick to what the manufacturer dictates. For it you have a claim and its discovered you've exceeded your recommended oil change hours/date, then the type of oil you are using won't be worth squat.

[Schooner Chandlery]

Originally Posted by Highlander40

Along with the longer interval, Amsoil recommends using EA oil filters(yes an Amsoil product) It is a micro fibre fabric that will hold more dirt before clogging up. I have used similar depth style filters in industrial applications and the life is several times that of a standard pleated paper.
Relating to marine diesels- A second oil filter called a bypass filter will also extend the oil change interval. It is much finer than the main filter and only a portion of the oil flow goes thru it. My Yanmars have them as standard equipment with a 250 hour interval.

I have a small diesel generator. Single cylinder, no oil filter. inside an enclosure. oil capacity 1 qt. This is a perfect aplication for synthetic oil. Lots of heat and the oil must suspend all the dirt.
Regular oil vaporizes and thickens, Amsoil doesn't.

In my cars, mileage is not an issue but I like changing oil once a year and I'm done. No standard oil will be stable that long.

We also use Amsoil in our Cummins 5.9L engine (4 gallons of oil) with the double oil filter (bypass filter) system installed. We get oil analysis done every 200 or so hours. We have changed the oil every 500 hours. All the oil analysis looks good on the oil front but we have had a lot of indicators (seem to recall silica) that indicate our air filter wasn't sufficient for the job -- too much dirt getting by -- so we recently changed from using K&N type oiled filters back to a non-oiled filter (sorry don't recall the brand) as we couldn't get good paper filters for the engine easily.

Oil analysis in itself is a great thing whether or not your oil is synthetic because it gives you a warning that you've got specific kinds of wear (can tell from the metals that show up in the oil), oil condition, as well as air filter sufficiency.

We have not changed our Hurth transmission fluid in 5 years / 1500 engine hours and while it still looks red and smells right (not brown or burnt) we are remiss in not checking into frequency further and need to change it as well as swap out the transmission oil cooler (raw water heat exchanger) as we think the transmission and it's heat exchanger are our most likely *weak link* at this point.

Fair winds, Brenda