is using fully synthetic 10/40 superbike oil ok in my Fat bob, some say its to thin others say ?
whats the score then, you guys over there have been running fully synth for years yes? any probs?

 

Use a 20w50 and forget about it. Duane5157

 

The only time I've switched to 10w40 was during the early winter months when the roads where still clear and temps in the 30's. Other wise it's M1 20w50 syn., IMHO 10w40 is sort of thin for everyday riding.

 

Air cooled engines run a little hotter. 20w50 would be more suitable.

 

Mobil1 20W50 V-Twin is for Air cooled engines, the super bikes are liquid cooled.

 

I run 15/50 Mobil 1 in every bike here. Works fine and you can get it at Wally World. Good in summer and winter as we ride year around down here in the south. Don't know anyone that's run 10/40 in a Harley.

 

you see you mention temp a lot, I live in the North of England in the hills and its bloody freezing most of the year, so cold the Roman Army could,nt stand it so even they pis$ed off. average temp of say 12'C or 55 F.
so would that make 10/40 ok?

 

don't think I would ever run 10w40. I run 60 wt. currently. Of course it's about 1000 deg. here in Florida. No sewing machine noise at all.

 

The magic temp, according to both of my owner manuals is 40 degrees F. (4 C.) for the 10w40 for engine oil. The 15w50 Mobil1 syn seems to be a good compromise.

 

Oil Thread opinions are like A**ho**s, everone has one----I have run 15/40 Syn Diesel in my Sportster Sport for 4 years without problem----ran in my 07 FXD until the run to Sturgis in the 90 deg+ weather, then 15/50 Mobil, will go back to diesel in the fall

Very cheap in the US