Bonneville America Forums Forums Technical Forums General Tech 10w/50 or 20w/50

The book recomends for 10/50 but what would be the harm in using 20/50 oil here In Texas were it really doesn't get very cold, but can be brutally hot?

I've used 10w40 year round since my bike was new (2004). It gets hot here too.
I put in 20w50 one summer and watched my gas mileage drop by about 3mpg and the starter turned a bit slower (worked harder) as well.

I was using 10/40 and my bike was running noticeably hotter than with the 20/50 I currently use. Difference of about 20º on the temp gauge, same brand of oil.

I run 20/50 here where our summers can be brutally hot. Interesting comment about the mileage, Bill.

Been running 20w50 since new.

I would never mention that I run Amsoil even if I did run Amsoil since I thought this was about viscosity not Amsoil or any other brand besides Amsoil. So far be it from me to mention Amsoil, I would only mention Amsoil if asked what brand I use, then I would have to say Amsoil. Since I wasn't asked I will refrain from saying I use Amsoil even if Amsoil is my brand of choice.

Have been an Amsoil dealer since the 70's when it was called Amzoil but that is neither here nor there. If you run these aircooled engines hard like I do go with the 20-50 it adds a little extra protection. As stated the 10-40 gives a little better fuel mileage but to me protection vs. fuel mileage is a no brainer. If I can afford the bike I can afford the fuel and we are just splitting hairs anyway.

I switched from 20-50 to 10-40 last spring only because of the hassle of getting it through the mail from the dealer. Haven't noticed any difference although I don't have an oil temp guage.

Ian, I appreciate you not bring up the brand of oil you use and keeping this thread on track.

Same here.....All I have to keep telling myself is .....this is not an oil thread....It really isn't... I don't have to comment.

I'm using 15w-50; like my manal recommends....haha!

Triumph has changed their recommended oil from the Mobil 4T 15W-50 to Castrol RS4T 10W-50 which is what I used on my last oil change. I assume the new manuals will reflect this. The recommendation is for all their engines, not just new ones.

Castrol got the new contract to make their oil. lowest bidder crap...........>:(

Chad, supposedly, the new Castrol RS (reduced slippage) is designed to work better with wet clutch motorcycles. I've put a couple of thousand miles since changing to the new Castrol. Can't really tell much difference, but the bike is running great.