What Oil Do You Use - I/Os?

[Chromaflage]

For you others who are running I/O's, what kind of motor oil are you using? My theory is that these motors are typically running longer at higher RPMs than a car would be, so I'm not sure if standard motor oil is the way to go. Do you run performance type oils, synthetics, etc?? What viscosity?

Thanks

CrF

[salmonfever]

Full synthetic-as recommended by Volvo. I can't remember the viscosity

[Pilar]

'KISMET' came to me with refined tastes in oil. So I stayed with that plan since the original 350 V-8 lasted 25 years and 1290 hours. The engine finally caved under severe use and I believe overheat and developed a block crack. When I broke the engine down to survey the damage the bearing wear was barely detectable. And the engine was really clean with no deposits.

Of course you have to be sure you are not leaking or burning oil first. But Synthetic oils work pretty good on I/o motors. The advice I got was to avoid multiviscosity types of oil for boat engines. It is unnecessary since the operating conditions are pretty constant.

I use Royal Purple synthetic in 40 wt. about $25 a gallon or $7.5 a quart. Some Napa sell it and Baxters and Autozone. If they do not have straight weight then they can order it. 50 hours per oil change and it needs it when I am running hard all day trips. 4 trips to the oil change. Standard mineral oil only lasts 25 hours. Synthetic oils will take more abuse and last twice as long at twice the price. Cost wise it is a wash.

[flapbreaker]

I hear good things about mobil 1. Costco sells it.

[FINZ]

Mobil 1 Full synthetic. When I bought my boat last lear the previous owner replaced the stock merc. 5L with a 5.7 Kodiak marine motor and that was what he ran for oil. So I'm sticking with it.

[little doc]

Find out what your manufacturer recommends. Mine recommends 15-40 dino oil.

Scott.

[CR dog]

Mobil 1 15-40. After 11 years and 1300 hrs the engine is still strong and running like a champ. I also don't go beyond 3200 RPM's. V-8 350 volvo duo prop.

[Orca]

Rotella-T Synthetic. Designed for heavy duty applications, great additive package.

[Don't fish e nuff]

Straight old 30 wt. That's what the mfg recommends. I do stick with Chevron Delo 400 though. I spent ten years as a diesel mechanic at a Saw mill and changed allot of oil and cracked allot of motors open. I am a firm believer in it is how often you change it, not so much as what you put in it.

[Bluefinn]

Dello 400 30 wt and change often.I buy it in bulk and change it often.Like two tuna trips change the oil every 4th trip change the oil and the filter.The guy I bought the boat said change your oil often and this motor will last you.I rebuilt it with 3900 hours on it stil running strong before the rebuild .I just thought it was time. to rebuild itI pull the boat maybe 3 times a season and change the drive oil.I was lucky my drive took 30 wt oil also 2.9 qts for the drive.My diesel truck uses the same oil.the wifes car etc.It just worked out for me to buy a drum.Not for every one though.

[BalouSC]

I run Amsoil in everything I own. Its good stuff. I am a skeptical person by nature but couldn't deny what it did for my friends toys and equipment. I finally caved. I am happy I did. If you would like more info, PM me. Balou

[backlash442]

Current IO what Merc recommends. Last IO which was Volvo I don't really remember but don't think it was anything special. Used to do it about every 100 hours.

IMO what's more important than changing your oil (ok maybe just as important) is making sure your manifolds and risers are in excellent shape. Absolutely nothing good about getting saltwater into your pistons. You can change your oil all you want but if you don't stay on top of the manifolds you will be replacing an engine no matter how often you change your oil.