how much oil should i use?
 

My 502 mag was rebuilt last year, and it has about 95 hours on it now. Completely stock.

Since my last oil change (2-3 weeks ago), the motor has burnt approximately 2 quarts in 20 hours. Is this normal? Should i be burning any oil at all?

There is a slight film on the spark arrestor where the breathers attach, is this where it's all going? I don't see any blue smoke coming from the exhaust.

I check the oil before i take off every time, and it seems that the harder i run it, the more i burn. If i'm just idling around or taking short cruises, it doesn't burn much if at all. But on Sunday i took about a 95 mile round trip running 3500 rpm most of the way, with a couple of blasts of WOT. That seemed to knock it down at least half a quart (probably 4 hours total running time).

Re: how much oil should i use?
 

All stock 502's have a light tension oil ring installed on the OE J&E pistons. They use oil. The harder you run the more oil you'll use.

1 quart per 10hrs is not unusual.

Now, that said, you may or may not have issues. If you are worried about it have shop that installed/rebuilt motor do compression and leak down test to make sure it is okay and broken in right.

Re: how much oil should i use?
 

My 502 mags owners book stated 1qt every 5 hrs is normal.

Re: how much oil should i use?
 

Dave -

Before I pulled my stock 502 with 80 hrs on it for a blower install, I went through about a quart every 10.

BTW...Did the recirculating water pump I sent out work OK for you?

Greg

Re: how much oil should i use?
 

It would be interesting to see what happened if you went to a significantly less volitile oil...synthetic of course..

Re: how much oil should i use?
 

How did I know that was coming :D

Re: how much oil should i use?
 

Water pump seems to be working out great... thanks Grog.

It's somewhat comforting to hear you all saying it's normal, but i may just do a compression and leakdown check to see anyway. One would think that a freshly rebuilt motor shouldn't use any oil... but i guess with marine BBC's we're talking about 25 yo technology, not modern car stuff.

Re: how much oil should i use?
 

LOL :drink:

I'll add, my 540 used close to 1 quart every 5 hours or so it seems, last year which was the first 40 hours or so. Was running Valvoline 50W Racing.

This year I'm running Amsoil 20w-50 Severe Service Racing and at 10 hours I added just a tad under 3/4 of a quart which turned out to be a tad too much; 1/2 quart would have been perfect. I had to find that by checking as oil pressure has been more consistant. With the Valvoline I'd either catch it in pre-run checks or see oil pressure start dropping at speed which told me it was time to stop and top it off, again. So............... :D

Re: how much oil should i use?
 

Maybe i'll go back and study that marine lubrication thread for awhile and see what i come up with. I'm willing to pay twice as much for oil if i burn less and can leave it in twice as long.

Re: how much oil should i use?
 

don't forget, way-different conditions than modern car stuff-especially if you compare production marine components vs ulev (ultra low emission vehicle) engines.

marine applications have constant load all(most) of the time. Kinda-like going up hill in a car at WOT, fuel washdown and RPMS play a good part at oil consumption.

I would take hydos sug (after you satisfy your leakdown and compression querry) and switch to a full synthetic; imo mobil 1 15-50. My oil consumption we down almost 1/2 from from a mineral based oil in a couple 502's.

Good luck on your leakdown