Had the motor (502 mag) rebuilt this summer, changed the oil at 8 or 9 hours then again at 20 hours. I asked the shop and they said "you should be good for the summer" (this was late august, early september). Well, i think my idea of the summer might be different from theirs. I'm coming up on 60 hours now (40 since last change) and i'm wondering if i should be changing it. I will probably only put another few hours on the boat this year, and was hoping to put off changing the oil again until spring.

change it after your last run THIS season. Changing oil at winterizing will get all the condensation out for the cold winter.
There is no other choice.

And, cut apart the oil filter and inspect it for metal flakes. Personally, I never let them go over 20 hrs between changes. cheap insurance.

I like to have all our customers with BBC's change there oil every15 to 20 hours with normal running. If they run the boat hard or have super chargers I like to see them changed every 15 to 20 with hard running. So far this has been a great program for them.

As stated earlier, you do want to do an oil change at winterizing do to the acid in the fuel and oil as well as some moisture in some cases. You don't want to leave that dirty stuff in there for the winter sitting on the bearings and stuff inside there, not good.

John S.

I run a pair of stock 502's. 25 hrs oil changes w/ Mobil 1 15/50 (synthetic), 50 hr drive fluid changes. Change at winter layup no matter hrs since last change.

i change my supercharged 454 every 15 hours.

Should i change the oil again in the spring if i change it before i put it away? I would think i'd get a lot of condensation over the winter that i'd want out of there.

I was putting 8-12 hours on my boat per weekend this year... if i changed my oil ever 15 hours that would be almost every week! I change the oil in my car twice a year with synthetic. I think my dad gets the oil on his boat changed maybe twice a year, and he puts on a bit over 100 hours a year.

I'll probably aim for a 20-30 hour oil change interval. I'll send in a sample or two for analysis next season and see what it really needs.

changing the oil at 20 and the drive at 40 (every other oil change) is cheap insurance...

20-25 hours TOPS, depending on time and weekend schedule (with synthetic Mobil1.)

Why do you say synthetic?

I've been told by multiple people NOT to use synthetic. I think mercruisers website even recommends against synthetic. what i heard was that it's too slick and that the rollers on the rockers and/or lifters don't spin as they should with synthetic. might be BS, but i'm sticking with the regular quicksilver 25w40.