From:Tom Wilcock
Subject:RE: oil for early K Date:Sun Aug 24 06:27:17 2014
Response to:5314
Graeme: My theory is that these old engines depend on lots of oil being splashed up on the cylinder walls and underside of the pistons to help in cooling. A lighter oil will give you more flow through the bearings with the result of more oil being thrown up to the top end. I have always used 10W40 in my 1940 Indian 4 with no issues. I have over 70,000 miles on the engine and it still shows 40 psi oil pressure. The Indian oil pump has a bypass. I think it is better to have more oil going through the bearings than out the bypass. My KJ is in the works and I plan to use the same 10W40 in it as well. This is just my idea so don't try this at home. Tom

it's hard to buy stright 50 weight oil and with modern technology why wouldn't one use a multigrade oil? Question is what do people out there recommend these days folks?