I did as search and couldn't really find any recent answers. I'm changing the oil in my Searay tomorrow and wondering if there's a benefit to running synthetic. The motor is just the small 3.0 Merc, but I load the boat down pretty heavy (for the kind of boat that it is). I use Mobile 1 in my vehicles. Also what weight would you recommend in Texas weather. Thanks in advance.

Being as your boat is a 90, I would say no unless you changed out seals. I know this applies to car engines, however, I cannot say for sure with a boat engine. If I were you, I would call a dealer and ask to be sure. Maybe one of the dealers here can chime in. Most older engine's seals will not stand up to the straight synthetic oil. They will at first, but the seals will also begin to lose their seal and leak eventually. Personally I would just stick with the standard synthetic blends that are sold. Also, unless you've used synthetic from very start (which wasnt an option in 90), there isn't much benefit in changing over except for a longer oil life. <BR> <BR>(Message edited by bac on April 04, 2008)

Best thing you can do for your boat is change the oil at least every 50 hours, beginning and end of the season. With frequent oil changes im just not sure theres as much benefit to using synthetic oil?

I'm with Byron. Just change it every season like you should. <BR> <BR>I'm not sure there is ever enough of a benefit from synthetic oil vs. conventional to make it worth the extra expense. thats for cars or boats...

and make sure to use marine grade engine oil. <BR> <BR>automotive generally not designed for marine enviroment. ok to use but better to change it more frequently if you do.

OK thanks guys. I change the oil regularly but didn't know if making the switch would free up some horse power/save a little gas.

probably not enough to notice in that little motor. <BR> <BR>you are probably putting alot of stress on the drive and engine if you are sacking it out and loading it with people, i would consider probably selling the boat and getting something with a v8 if you plan to hold onto it for a long time, if you dont plan to keep if for more then a year or two before upgrading to a wakeboat. id just save the money run regular oil and save the money in your wallet. kinda like jumping over dollars to pick up pennies.

Mobil 1 exceeds all the marine specs from 1990. The viscosity number to use would be the same as the higher number on you engine spec. (ie. if your engine spec is 30 then any synthetic with a 30 would be fine, like 5w-30, but not a higher weight like 5w-40) <BR>If you are presently burning or going through oil in your engine you will go through more synthetic so it would just add to expense and I would not recommend it. <BR>If your engine doesn't use oil now there are benefits to using synthetic. You have easier starts, longer service life, better high temperature protection, and slightly higher power output. I would put it in if my 3.0 engine was not using oil now. If you find you are using more oil, just add conventional instead and go back to conventional next change. <BR>You can mix synthetic and conventional oil without problem and you can use it on old engines. It just flows better so you lose the more expensive oil faster if you've got leaks.

I'm not burning or leaking any oil. This boat just has to last one more summer. I'll be getting a wake boat next year, but a baby on the way so that's going into next year's budget. Art do you think the added cost of Mobil 1 would be worth it for one year? Also anyone have any little tricks or tips to get a little more power? Have repitched prop etc., so just motor tips.

I had an 02 searay. the OM said specifically do not use synthetic oil. i don't know enough about the stuff to know why.

Over 1 season and selling the boat you probably won't notice any difference, so it's just extra expense. That said Brandon, I'd probably put it in anyway. (but I'm often dumb)