Oil in sitting jet ski engine...time change interval or mileage change?

[deagle]

Really engine related, but you guys are the smart ones.....

I have a 4 stroke jet ski. Spring 2013 I changed the oil with amsoil as always. Wife pregnant so we only used it once for about an hour. This year I skipped the oil change. We probably were out on it 3 hours one time. Oil interval change is every 50 hours.

So I have synthetic oil with only 4 hours on it, but been in the machine for two years. Doesn't oil really break down from shearing/heat/dirt, etc? Is there really any need to change oil that is just sitting?

Thanks,

Don.

 

[Fred W]

Me? I wouldn't worry about it. Oil doesn't break down from sitting in the engine.

But, I'll tell you the "conventional wisdom": People will say that once the oil has been used it will then contain corrosive combustion byproducts in solution, which will cause problems with the engine during "long term" storage.

I say BS. I've never bothered to change the engine oil early just because it may be in storage for a few months over the winter. Just change it when it's due.

YMMV

 

[HotRodZilla]

What Fred said. I wouldn't stress it unless it was a bunch of short trips where the motor never got to operating temp. When I say a "lot," I mean, like 30/50 hours of that.

I'd say you're good.

 

[TomInPA]

I would be in the same camp as Fred on this one. The oil is not so much of a concern, but long-term storage of an engine should include draining fuel or use fuel stabilizer and possibly fogging to prevent corrosion. The oil is unlikely to contain significant contaminates or contribute to corrosion...bare unprotected metal on the other hand not so much. If you're not going to run the engine, over a course of years, fogging seems like a good precaution.

 

[Top_Speed1]

Really engine related, but you guys are the smart ones.....
I have a 4 stroke jet ski. Spring 2013 I changed the oil with amsoil as always. Wife pregnant so we only used it once for about an hour. This year I skipped the oil change. We probably were out on it 3 hours one time. Oil interval change is every 50 hours.

So I have synthetic oil with only 4 hours on it, but been in the machine for two years. Doesn't oil really break down from shearing/heat/dirt, etc? Is there really any need to change oil that is just sitting?

Thanks,

Don.

Not sure what model 4-Stroke you have? and I say that only because if you have a super-charged model>... it changes the outlook. If it's NOT SC'd. (naturally aspired), I'd wing it as prior mentioned^^^

. If you do have a SC you may think twice. The cost of new oil and a filter is pennies on the dollar compared to having your SC rebuilt. I've now since learned how to shim and rebuild the SC's myself and most failures seem to always be lubrication related. They seem very picky on oil, especially the ones with ceramic washers. It may seem crazy to outsiders like the biker crowd here, but these SC spin at unbelievable RPM's and seem to be very fragile with longevity in mind.

Hope this helps. I've owned and worked on hundreds of skii's before. Oil is usually not any issue as others here have mentioned, but if you do have a Super Charger?... just change the oil/filter out. Peace of mind as well

 

[Fred W]

You think superchargers are tough? Try turbos. A turbo has the same compressor issues a SC has, but being driven by the exhaust it also has to deal with extreme heat on the drive turbine. And the bearings have to be very free wheeling or no spinny, no boost!

I've owned a bunch of turbo cars, most were SAABs, but also a Dodge a while back. They are very picky about lubrication, and require specific full synthetic oil to be used to prevent coking of the oil in the turbo bearings. But that's pretty easy to avoid, just use the factory recommended Mobil 1 0W40 oil at every change and Bob's your uncle.

Even on those turbo engines the oil change interval is pretty long (7500 miles) and there is no need to stress about leaving dirty oil in the engine. I've got 100k miles on one and 165k on another one using the 7500 mile changes and both are running strong with good boost.

When you think about it, the engine has dirty oil in it every day of its life, except for the few minutes right after you actually change it.

 

[Top_Speed1]

You think superchargers are tough? Try turbos. A turbo has the same compressor issues a SC has, but being driven by the exhaust it also has to deal with extreme heat on the drive turbine. And the bearings have to be very free wheeling or no spinny, no boost!
I've owned a bunch of turbo cars, most were SAABs, but also a Dodge a while back. They are very picky about lubrication, and require specific full synthetic oil to be used to prevent coking of the oil in the turbo bearings. But that's pretty easy to avoid, just use the factory recommended Mobil 1 0W40 oil at every change and Bob's your uncle.

Even on those turbo engines the oil change interval is pretty long (7500 miles) and there is no need to stress about leaving dirty oil in the engine. I've got 100k miles on one and 165k on another one using the 7500 mile changes and both are running strong with good boost.

When you think about it, the engine has dirty oil in it every day of its life, except for the few minutes right after you actually change it.

Turbo's are similar (job wise) but not nearly as many RPM's. I've changed/upgraded the turbo in my Duramax Diesel (along with many of other performance things... called "bombing"), I found that not nearly as complex as the SC on my skii's. Big difference (beside longevity in Turbo's) ...we do not want the "Spool up" or lag time to compress. The SC drives off the actual engine (geared to) and is such a temperamental week link in our skiis and most failure comes with breakdown of interior parts due to wear or lack of lubrication. It's inevitable (eventually) in all things with friction, just WAY more-so here.

I know you got a million miles on the bike vs me, but the reversal here is that you now have stepped into Top Speed's world

Cheers Fred, enjoy that new toy!

 

[HotRodZilla]

Top speed has a world??!! Just 'effing great!

 

[deagle]

thanks for the replies. Ski is the STX1200 model. No SC or turbo. And I'll winterize (antifreeze and fog) this weekend as always for Winter. But I'll skip the oil change again.

Who know babies took away from your free time???

 

[Top_Speed1]

Top speed has a world??!! Just 'effing great!

You better know it, AJ!