View Full Version : Oil Change question on 81 MC

06-28-2011, 04:57 PM
I downloaded the owners manual and PCM repair manual, thanks to this site, but still had some dumb questions or better yet verify what I have figured out with the experts. This is a new to me boat, so want to make sure everything is good to go. Went to check the oil and can't get an accurate reading on the stick, the side with the words only shows a small amount, the other side shows more. So figured I would just change the oil and start fresh.

Looking at the manuals it seems I should run a 20W-50 wt oil, made for flat tappet engines, use rotella, etc. . Run a motorcraft FL1 filter, my question is what is the capacity 4 or 5 qts and do I drain it using the rubber hose with the threaded nut on it and push through the drain hole under the motor in the hull? Thanks guys

06-28-2011, 05:11 PM
Ya, that hose is it. Warm it up to operating temp first or the oil will drain super slow. I have an 84 and I use 15w40. Hope this helps

06-28-2011, 06:24 PM
agree with the above.
1. Warm up (with water running thru, fake-a-lake as a minimum).
2. Kill engine, turn off water supply.
3. feed hose thru drain hole, put oil pan under, remove cap on hose to start draining into pan ...

...while engine is draining thru hose,

4. put rags or better yet another drain pan under filter.
5. remove oil filter and place in pan.
6. Rub a little oil on new filter gasket.
7. put new filter on and hand tighten, only filter wrench tighten 1/8-1/4 turn past hand tight (unless you have kung-fu grip, then no wrench!!!)
8. put cap back on drain hose under boat & tighten.
9. pull hose back into engine compartment.
10. put 4 quarts oil in (I always used Castrol GTX 15w40 in my old '83 S&S).
11. re-connect to water supply & turn water on,
12. start engine, and keep close eye on oil pressure gauge (it should quickly start showing pressure, shut down if no pressure shows in about 10-15 seconds max).
13. kill engine and turn off water supply.
14. wait a couple of minutes (so oil drains down thru engine back to pan), then check engine dip stick. it "should" show in the lower area to the add 1 quart line.
13. add oil to bring up to full level.

Bruce Carr
06-29-2011, 10:13 AM
On my '83, with the oil filter filled with oil (after running a minute or two to fill it up), 4 quarts shows to be full on the dip stick. The engine should hold 5 quarts. I have read that there is more than one version of the dipstick and I probably do not have the correct one even though the dipstick I have is the original from the factory. I filled the engine with 4 1/2 quarts of oil and made a mark on the dipstick at that oil level. Works for me for the last 28 or so years...

06-29-2011, 11:38 AM
Thanks guy's, the guy I bought it from said the oil needed to be checked with it in the water. But I have the boat level in the driveway and it still is not giving me a good reading. I am going to dump the oil, change the filter and mark the dipstick.

06-29-2011, 12:10 PM
I have never checked mine in the water. Always on the trailor or in my lift.