Forum

[Signature1800]

Hi, What is the best mono grade ENGINE oil to use in my 1988 350 Bullet or should I use a multi grade 20w/50 ?

[Tim NZ]

DONT use a monograde engine oil! Monograde oils are only suitable for a specific set of steady/constant/continuous operating parameters

[Signature1800]

thanks Tim NZ, as I am here in Australia can I use a multi grade Castrol or similar?

[PeteF]

Any decent 20/50 will be fine.

[ed.lazda]

Tim, your advice makes sense to me and I always use multigrades in bikes of any age. But there are some very knowledgeable people around who would disagree -- for example, Les Emery at Norvil, who has probably built more engines than I've had hot dinners, is ADAMANT that you MUST use monograde in a Commando. Any idea why he (and others) think this way?

[Revband]

Good question Ed, I for one don't know, I used monograde for many years in many bikes with no problems, I have used classic multigrade now for many years without problem basically because it is readily available, again no problems, as a hard up teenager I used second hand oil drained from my dad's car in my BSA B31, thrashed if everywhere again no problems, any oil is better than no oil it would seem.

[Alan R]

Hi Guys-----SIGNATURE..here are two reference points}---1) Go to page 7 of our hosts 2017 / 2018 catalogue and have a good read-up.....2) What does your owner's manual say on the subject ??

I'm with TIM and PETE F on this........In my Iron barreled, 500cc Bullet '65 I use Morris Oils 20 / 50 mainly because it's formulated just up the road at Shrewsbury and I can get it VERY cheaply from my nearest Farmers' shop outlet !!.........Changing oil at the recommended frequency along with a fresh filter and then riding your bike with a "sympathetic ear" will ensure longevity more than anything else I would say....

[binary]

Gulf Western 20/50 that I buy from Supercheap Auto parts and accessories here in Tasmania Australia. The 20 part is for when the motorcycle is cold and it is then pumped around much quicker at this lower viscosity and the 50 part is for as the oil heats up polymers in the oil change its viscosity to this higher number so that it better protects the engine at running speeds, at least that is what I have been told. Multi grade.

[Tim NZ]

Ed:


Notrun Commonwhores have much bigger problems than what oil to run: Flexing crankshafts, stripped exhaust port threads, cracked cases (eng & Gbox) engine breathing, cam and tappet wear, I could go pon and on and on...







Multi grade Synthetic or Group 111 mineral oils (premium) have it all over any 'Straight' oil for ANY motor that is expected to operate across a broad spectrum of operating conditions.


Rather than run a mono-grade oil for any street based motor-cycle, Les would be better served by fitting a thermostatic controlled oil cooler. Bugger me if that is not the rest of the automotive world does?


There are valid argument for Mono grade oil, but only if you are comparing Supermarket brand cheepo take home packs of multi grade compared to a premium #straight oil. That are not going to be changed in under 2000miles. The situation was worse for the pre 73 Notruns that did not originally have a decent oil filter. Exasperated by extreme cam/tappet loading (DONT run SSS cams) and high pistons speed that all accelerate oil shearing (breakdown) and oil overheating. Norton oil tank temps of over 120c are common, along with big end temps in excess of 50c: The Motors are seriously dated and have poor thermodynamics and cooling.


Make you wonder just who has it right...

[Alan R]

Hi Guys---------OOoopppsss BINARY, you've fallen into the old "Viscosity" trap I'm afraid....Consider this}----Before you change your old oil you take the bike out for a run to heat it up so that the oil will drain better, yes ??...Now if what you have just said ( and 1,000's of others also do I suspect ) then you'd have to book your bike into an industrial meat freezer so that the oil would come down to a 20 grade and thus flow freely out of the sump..... Clearly that's not the case, so what is going on ??............

Have a read of this to get a better understanding}----- PS}--
the sign cSt means "Centistoke" and is a unit if fluid/mass flow rate...1cSt = 1 square mm per second------ http://www.belray.com/what-exactly-do-m ... tions-mean