Hello, I’m new here and just purchased a 2004 bonneville t100 and was wondering what oil weight to use? The previous owner was using a combo of 2quarts 20w50, 1quart 10w30 and the last being 5w20.
The brand? Castrol gtx for all.
The PO was a mechanical engineer and had plenty of convincing reasons as to why I should use this mixture- I’m thinking I’m gonna stick with it unless convinced otherwise. Thanks View attachment 759962 View attachment 759963
Interesting observation. I stopped using 20W50 because I thought it was too thick and made the bike too hard to start from cold. The Mobil Racing 10W40 motorcycle oil I put in there now is noticeably thin compared to the Amsoil 20W50, and that might be better. It certainly made the bike easier to start. Maybe it saved my oil pump gears too.With plastic oil pump gears, using a thick oil on a cold start will put a lot of load thru the plastic - not good.
Duckman,NONE of the oils in the posters photograph are suitable for use in a Motorcycle. The oil must have a JASO specification. Jaso Specification means suitable for wet clutch. Mixing weights on fresh oil change is just plain stupid and serves no purpose. This "mechanical engineer" was just getting rid of crap he had in the garage or should have his license revoked.
I originally ran Triumph branded 15W50 Mobil 1 until Triumph discontinued it. Then Mobil 1 20w50 VTwin until it stopped being a JASO oil. I ran Royal Purple 20W50 MaxCycle until recently. At 134,000 miles (215,000km) my oil consumption has climbed to 1 1/2 quarts in 3,000 miles. Just Switched to Redline 20W60 in an attempt to slow the burn. A straight weight 50 or 60 would have been preferred, but the availability is virtually non existent. This bike is ran hard in 100 degree temperature on a regular basis. When I am touring and low a quart, Shell Rotella is JASO and available almost anywhere.
Everyone has a brand preference. Choose a name brand synthetic motorcycle oil.