Volvo Penta 275, 280 oil type

I hope someone can assist - Volvo recomends "engine oil" on the 270, 275, 280 stern-drives. These drives are old-design and seem to be too tough, so I would expect the safety factors are all low and the surface pressure on the gear teeth is small.

My feeling is the engine oil is "good enough" but I questioned Volvo if I could use proper gear lube on it. They simply said "not necessary". But I don't mind - still the cost is roughly the same... I can't understand why to lube gears with an oil designed for an engine (where detergents are needed, for instance and temperatures are high) whereas an oil with high pressure shear resistance would be much better. All gearcases I had seen (I am not experienced on this subject) do use gear oil. An exception is motorcycle and the sole reason is that the gearbox and engine are on the same box (fine design compromise to achieve low weight and footprint).

Does anyone uses gear oild on these Volvos? Which viscosity (I guess I should go for 75W80 which is by my memory the lighter one for this purpose).

 

Generally, the pressure on tooth surfaces is immense in all stern drive gearboxes, so a hypoid type lubricant seems the best choice to me. But the old Volvo's were probably sturdy enough to survive on engine oil.
A marine quality oil with an additive to prevent emulsifying certainly is appropriate.

 

According to my Seloc manual, some of the later models did call for gear oil, though it could have been for 290, SP's and DP's - but with the exception of the DP, all the aq's and sp's are pretty much the same internally. So if you're worried, I don't think gear oil can hurt anything but economy.
For what it's worth, we ran engine oil in a 200 series Volvo behind a 240 hp v8 for over 30 years before it failed. Granted were in a colder climate; but I'm sure it was over 15,000 hrs.
I use Rotella 15w-40 diesel oil in my 270 now.

 

volvo's have an internal pump that oils the top gearset, be careful that you don't starve the top with thicker oil. volvo are the most reliable leg you can get i don't see why you want to change from the recomended oil, it has proven itself over many years. i would not use oil additives either, cone clutchs might not like it. i personally have owned 2x280 legs, 2 100 series, 1 250. i love them , i don't think any other brand compares with them in the older legs.

 

also we run 30 grade engine oil in roadtrain gearbox's and they pull 120 ton around for a million km between rebuilds.

 

Racers would use auto tranny fluid ATF for less friction.

I mean it has a pretty good cooling method. Total submersion of the gear box in water,-- can hardly be improved upon.