Synthetic or conventional drive lube.

[smokinbob]

synthetic= Alisyn 80W

I can't say enough about Alisyn, great product. I'm alway's surprised at how clean the lube is with barely any "fuzz" on the magnet. Running XR's w/IMCO lowers behind 800+HP.

[Bobcat]

[ryan9154]

I was running royal purple switched to amsoil severe gear.Ran one drive with royal, one with amsoil gears looked brand new with the amsoil,other ones were fine but had some discoloration,ran for 62 hrs like that before I took them apart.Running 702 hp with upgraded bravos 280 hrs on them.Amsoil all the way!!!Buy it in bulk can ship anywhere.

[Wobble]

Mobil 1 Synthetic Gear Lube LS 75W-140

I fail to see why "marine" is important, it's not that hard to seal an outdrive. Otherwise it's just a gearbox

[Back4More]

I ran Mobil 1 75-90 with a lucas mix at about 10-15% for the last season and a half on cryo gears I bought from Smitty. I broke a lower vertical shaft last week and had the chance to open it up for inspection. The gears had almost no wear and the bearings looked good with exception to the propshaft gear bearing....by far the highest load carrier. The cryo was well worth the dime and I will never change from this Gear Lube recipe. This was on a 1993 non step/tank 42' Fountain, 800+ HP blower motors, 1.3 Bmax uppers with IMCO -2 lowers, on IMCO boxes, spinning 4 Blade bravo1 props.