10W40 vs 20W50

[MnM]

I tried searching but could you guys/girls explain what the difference is?

Thanks

[TheIglu]

The difference is how thick/thin the oil can be.

A 10w40 is a thinner oil than a 20w50. The two numbers give you an idea of the thinnest (10w) the oil can be and the thickest (40w) it can be within a given set of temps.

Warmer weather will usually mean a thicker oil since the engine runs hotter. When oil is hotter, it gets thinner. Too thin and your protection isn't as effective. So I run 20w50 during the summer in my old CB750F and 10w40 the rest of the year. The 20w50 stays thicker in the hot temps but would be almost too thick in the cold temps.

[bigred875]

Originally posted by TheIglu
The difference is how thick/thin the oil can be.

A 10w40 is a thinner oil than a 20w50. The two numbers give you an idea of the thinnest (10w) the oil can be and the thickest (40w) it can be within a given set of temps.

Warmer weather will usually mean a thicker oil since the engine runs hotter. When oil is hotter, it gets thinner. Too thin and your protection isn't as effective. So I run 20w50 during the summer in my old CB750F and 10w40 the rest of the year. The 20w50 stays thicker in the hot temps but would be almost too thick in the cold temps.

but in theis part of the country I dont think the 20w 50 is totally necessary...but it doesnt hurt...

I ran 20w 50 in NC...10w 40 here

[RandyO]

why not run 10w-50 get the cold starting viscosity of a 10w-40 and the operating viscosity of a 20w-50

10w50 is what RMS puts in my SV

[skiierx]

I am switching to 15w50! Best of all worlds for the twin

[KB]

I used to use drain oil in my last motor because it used more oil than gas...........

[Half Squid]

Originally posted by rmbbikes
I used to use drain oil in my last motor because it used more oil than gas...........

& Smoked more than a chimney during a cold Winter!

[MnM]

thanks for the info!
I just tried 20W50 for the first time...i used 10W40 before.