No brainier here 20W-50
An yes I ride a 1990 FXR so I do know
3 1/2 quarts.
Sunoco, makes Harley Davidson engine oil
80/90 semisynthetic hypoid gear oil is what the factory put in it but I use Red Line Heavy ShockProof fully synthetic gear oil. Not cheap but neither was your Harley.
5w30
5 quarts
5w30 or 10w30
Harley-Davidson Oil Pressure Specs for the Twin Cam Engine: Cold engine start-up: 44-50 psi. Warm engine at 2000 rpm and up: 30-38 psi. Warm engine at idle: at least 10 psi.
20w50
Just bought a Harley....what weight oil is recommend for this bike. Also, how many quarts does it hold?
It is important to use the right fluids in a vehicle to keep it running. The 1999 XR 600r uses engine oil 15/40 weight.
Gas 10w30 Diesel 15w40
If you use the same weight as The original oil, for example now the engine uses 15W-40, and you do an oil change, filling it with the same specs 15W-40 oil that's no problem for the engine.