Engine oil type and fuel consumption.

[Flyingpony]

Thought I'd share with you all a finding I've made to slightly reduce the running costs of my bike. A dollar saved, is a dollar saved. I'd expect other FXR owners to have the similar figures as myself.

Two years ago switched my FXR150 from the $10 oil put in during services by bike shops, probably was mineral 10w-30, onto fully synthetic (FS) oil. This FS oil was the cheapest found in bike shops at $15 - Shell Advance 15w-50. Bike only needs ~1l. Yes I know it's overkill to use FS oil, but it's my choice to run this commuter machine on it, please read on.

Prior to switching oil types the bike was running at 32km/l, and after switching to FS oil the it's now running 37.5km/l (economy figures are averages). Nothing else changed, just the oil type. Fuel consumption between prior services with mineral oil had no impact, so dirty sludge oil idea is ruled out. The monies saved on fuel covers the extra cost of that FS oil (Am no longer running this oil, it's now used as Loobman chain lube because I've switched to a thinner winter weight grade).

The reason behind this improvement isn't quite clear. It could be the reducing frictional properties of FS oil over mineral but I doubt this explains the entire improvement. What I think the reason is, FS oil is thinner when cold than mineral and because most of my travels are 3-7km long, the bike does more km cold than hot. This oil property has therefore reduced the amount of energy required by the engine to operate internal components bathed in oil - gearbox gears, crankshaft splash, oil pump, and etc.

As you have read, the type of oil you run can impact on your daily fuel costs. I'm not advocating that you switch over to FS oil, just providing another piece of information from the field. This field data is measured using the trip counter and amount of fuel petrol station pump has pumped.

[TwoSeven]

Youd get the same kind of performance from switching to a 10w30 to a 10w15. Simply put, less sump drag.

[Motu]

This is why the Yanks use such thin oils,they have to pass economy tests.Oil below 10/30 will definatly improve fuel economy - 0/20,0/10 are common now.Also on the dyno the thinner the oil the more power it makes - now why on earth would you want to use a 20/50?

[Zapf]

and just to throw a spanner in the works... try different make oil as well... you'll probly get different figure.

I know that oil without cleaning agents are even more slippery... but u won't use it on a daily basics