How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

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. :D

Re: How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

i change my supercharged 454 every 15 hours.

Re: How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

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

Re: How often should i change the oil?
 

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

Re: How often should i change the oil?
 

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.

Re: How often should i change the oil?
 

I use Castrol 20w50 conventional oil. It looks like golden honey when it is new and I change it when it begins to get dirty which works out to be something like every 25 hours or so. Conventional or the super sophisticated, expensive Synthetics .....when it's dirty none of it is any good!

Re: How often should i change the oil?
 

Mercruiser no longer does not recomend semi-synthetic, because they now have a semi-syn out under their label. :D

I saw a Merc service video once and the guy from Merc said the reason they said no synthetic was that synthetics did not have the anto corrisive additives needed in the marine environment.

I think:
1) if you're changing the oil every 20 hours, that won't matter
2) At least Amsoil had and has an oil specificly for Marine and Diesel applications which does contain the anti corrisive additive. I'm sure others do now too, but like I said, if you're changing the oil often, it doesn't matter.

In the 7.4 MPI I ran Amsoil 15w-40 HD Marine and Diesel but in the new motor I've been running 50w Valvoline Racing Oil and changed it at about 10 hours then ever 20 after that. Since March when she was first fired, I have about 45 hours and 2 oil changes with one due now.

Re: How often should i change the oil?
 

Change it!

Re: How often should i change the oil?
 

Good question. Can anyone comment? I don't think I would be comfortable running oil that sat in the crankcase all winter, even if it was changed in the fall.

Re: How often should i change the oil?
 

I'll run it 5-10 hrs in spring and then change.

The small amount of condensation will burn off.

Good point above re: acidity in the used oil sitting over winter.

Will do more damage than condensation.

Re: How often should i change the oil?
 

Eggzackly!! I use conventional oil as well. IMHO...it's a waste of $$$ to use synthetic if you are going to change it every 25 hours.

Re: How often should i change the oil?
 

In honor of all you conventional oil users I hereby post this.. :D

Re: How often should i change the oil?
 

20 hours period. Conventional all the way... until someone proves that synthetics do anything better than conventional at normal temps and 20 hour changes... :rolleyes: :rolleyes: :stupid:

Re: How often should i change the oil?
 

Has anyone done any kind of oil analysis to determine that 20 hours is the limit? At 50 bucks and a good hour an oil change, i don't want to be doing it every two weeks unless i absolutely have to. It takes forever to suck all that oil out through the dipstick tube.

Re: How often should i change the oil?
 

I've done a couple of oil analyses, and I probably could have gone longer. The oils I used (Kendall & Mercruiser) were hanging in there very well. But I think if I were pushing it longer I might go synthetic. These motors are pretty tough on oil...

I've never seen an oil analysis on synthetic posted.

Re: How often should i change the oil?
 

Same here...15-20 hr changes is what I do, and it is cheap insurance. Considing the cost of a rebuild, why skimp? In the long run the frequent oil changes are allot cheaper. Plus less down time and BS.

Re: How often should i change the oil?
 

All I'm saying is that at 25 hour intervals for changes and 14 quart pans, conventional oil is good enough for me. ;) I've had good luck for the last 22 years that I've owned a boat.

Do you even have a boat??? :evilb: :evilb:

Re: How often should i change the oil?
 

....who needs a boat when I have my very own short bus. :D

I had a couple offshore boats for about 12 years and I will be back in the game again...I miss all the headaches..I mean fun. :drink:

Re: How often should i change the oil?
 

I was about to ask this question again, so i did a search and realized i already asked it once.

I'm closing in on 20 hours on my motors. I think i'm going to push it to 30 or 40 hours for an oil change. I don't have the time or money to change my oil twice a month all summer, ****, that's half the boat payment again.

The shop that did the rebuild said 50 hours would be fine. In a car, if you manage 60 mph average the whole time, it would take 50 hours to hit 3k miles. Constant stop-and-go would take more than 100 hours.

My dad has 1100 hours on the 454's in his cruiser and he changes the oil maybe twice a season, which probably amounts to about a 100 hour interval. I run a bit harder, so i think i'm going to shoot for 30-40 hour intervals.