Oil weights
Posted by Harry from Black Creek, GA, US on May 22, 2007
This is out of the line of “trucking” but if you are an “Expert” on oil I want to see if you can answer this question.
This is for oil used in a motorcycle. The Yamaha book calls for 10w30 from 10 - 90F. 20w40 in temp. above 90. I have searched but all I find is 10w40. Is that safe to use or can you blend weights to achieve a 20w40. The engine only holds 3.28 US qts. We are planning a 8000 mile trip so oil changes will be made every 3000 miles.
In theory you could blend the two oils to meet the correct viscosity, but this is not reccommended for two reasons,
1. the oil additives within each oil must be identical and in the oil at the same quanity in order to ensure the performance of the oil is uncompromised this is very unlikely
2. The amount of 10W30 and 20W40 that needs to be added to reach the correct blend would be very dificult to calculate, as the viscosity of a finsished formula is the result of base oil, viscosty modifier and additive pack.
A 10W40 sounds like the perfect viscosty for your motorcycle, as this combines the cold performance benefits (for starting) of the 10W and the hot tempereature performance of the 40.
