Regardless of what engine, lots of benefits seen from switching to Alisyn drive oil. I gained 2 mph on a V6 boat, 454 mag nova gained 4mph.

My 15-40 Diesel oil experiment has ended,, and I will not be using it any longer in my 496.. going to stick with Castrol syntec synthetic blend 20-50.. After a VERY hard hour long run at lake champlain I found my oil pressure's at idle dropped quite significantly,, seems the lighter weight cannot keep the pressure up when it get hot..

DOn't quit just yet. Try Mobil 20W-50 V-twin synthetic. Liquid gold as far as pressures and protection go.

At the TMP shop they use 20-50, and tell all their customers to change every 10 hours. I have a quick oil change set up on the motors so it can be done in 30 minutes from filter to refill, plus it keeps my 1 year warranty in effect, to me oil is cheap insurance. Jeff

Just giving up on 15-40,,, it's not enough oil for our motors, after long runs, oil pressure suffers.

Wondering if mobil 1 15-50 will do the same ??

I wonder if I could run the 20-50. After long hard runs my temp after the cooler is barely 220. If I take it easy, cruising 3000 rpm I barely see 140.

ALISYN. its around 10$ a quart. On just drive oil (Alisyn Type 1, compared to merc racing) I gained 2mph on radar, I also had more gas than my previous best time pass.

Found a lot of information about Alisyn HERE: http://www.aerospacelubricants.com/c...listing=Marine

Tommy, wondering which gear lube you used in your outdrive ??..

I use Mercury Marine oil & filters.

Didnt mean to post twice with the same information.

I think it is pro gear. Type 1 I know for sure.