oil question?

Question

my motorcycle calls for sae 20w40, is it okay to use diesel 15w40? would it maybe even be better? i have heard somewhere to use diesel oil?

Answer 1

The only difference between the two would be that the 15w40 would be thinner in cold weather, which would allow the oil to flow better. Once it warms up the oil would have the same viscosity as the 20w40 oil. Diesel oil works well for motorcycle applications because it is formulated for high temperature operation.

Answer 2

Geez! Diesel oil WILL NOT "kill" your engine! I use diesel oil in my antique car and bikes because diesel oil has more zinc than the new, low zinc automotive oil formulations. Zinc lets metal parts slide across each other easier. New car engines use roller tappets which eliminates the sliding action between the camshaft and tappet. Most bikes don't use a roller tappet and thus the reason for using diesel motor oil. Beware that the latest diesel formulations have reduced zinc, I can't remember what the letter designation for thoe oils is...CF? Right now I don't feel like going out in the freezing rain to the shop to check. Look for a designation like CD or CE for the higher zinc oils. Otherwise look for diesel oils formulated for older diesel engines at farm supply stores like Orschelns, Tractor Supply (TSC) and such. I run Mystic synthetic conventional mix in my bike. The only thing I noticed was that when I first started using it, the clutch would slip under hard accelleration for a few days but has never done it since.

Answer 3

I have Rotella 5W40 full synthetic in three Hondas. In the past I've used Mobile1 15W50_ both from Walmart.

At one point, Harley-Davidson suggested the use of crankcase oil specified for diesel engines in the event that H-D brand was not available. Diesel spec crankcase oil has additives that other auto oils do not.

If you are riding a motorcycle with a wet clutch, synthetics have characteristics that diesel oil does not and will protect your engine better.

Answer 4

I's still trying to find the owner's manual, but I think that w/ my Buell, it does say if you have to use auto grade motor oil to use diesel grade.... but not your standard auto grade. And depending on the climate temp you oil viscosity specs will change.

Here you go.... found it

Engine oil is a major factor in the performance and service life of the engine. Always use the proper grade of oil for the lowest temperature expected before the next scheduled oil change. Refer to Recommended Engine Oils. Your authorized dealer has the proper oil to suit your requirements.

If it is necessary to add oil and Harley-Davidson oil is not available, use an oil certified for diesel engines. Acceptable diesel engine oil designations include: CF-4, CG-4, CH-4 and CI-4.

The preferred viscosities for the diesel engine oils in descending order are: 20W50, 15W40 and 10W40.

At the first opportunity, see an authorized dealer to change back to 100 percent Harley-Davidson oil.

Answer 5

wont hurt it, bikinkaw is on the right page, but left out the fact that diesel oil has a ton more detergent in it also. if you've ever seen used diesel oil you ll know why.

Answer 6

15w40 is just a little thinner oil. It'll flow through the case easier is all. Your bike engine is designed to use a specific weight of oil thats why they say to use manufacturers suggestion. As far as diesel oil, never heard of that one for a bike

Answer 7

Don't use diesel oil, if your bike runs on gas, it will kill the engine.

Best oil to use in any bike is...Synthetic oils.

Answer 8

environment.about.com/od/earthtalkcolumns/a/motoroil.htm