The new Yamaha FJR1300 recommends 20W40 Yamalube. I wish to use a synthetic type
oil and 10W40 and 20W50 are the usual types
that are available. 20W50 is usually an air cooled (V-Twin) type of oil. The Yamaha is
water cooled and a 4 cylinder motor. The call
to the Major Oil companies yields different
answers. How do you make a decision on the
multi weight oil to install in the motorcycle?
I know this is a splitting hairs situation but
help with an answer to make us feel good about
the type of oil in the machine that matters most to old bike riders. Thank you.

I am wondering if a 15w40 would work. I believe you can find it in synthetic at a number of oil companies (Royal Purple lists a 15w40), providing an automotive motor oil can be put in your bike. According to the API chart, a 15w40 will have a minimum high-sheer-rate viscosity comparable to that of a 20w50 (3.7 cP at 150C vs 2.9 for a 10w40). This would be particularly important if the gearbox is lubed with the crankcase oil.

Speak to your local Yamaha dealer about his recomendations. The oil you select is depandant on the climate you live in amongst other things.

For example Mobil has an excellent synthetic oil for 4 strokes with the Mobil 1 Racing 4T (15W-50), they also do a Mobil 1 V-Twin (20W-50) that I suspect is aimed at the Harley owners out there. Check the Mobil website for local info. Your local dealer can help you make the right decision on the viscosity needed, this should help to narrow down your search for the optimum oil.

Be careful using oils commonly used in cars, wet clutches do not agree with some of the additives in these type of oils and you will get clutch slip happening. Stick to motorcycle oils to be on the safe side.

[This message was edited by Lube MATE on Thu January 08 2004 at 11:07 PM.]

Larry,

Most synthetics lean towards 5w for the winter SAE numbers and SAE 30 or SAE 40 for the summer. So if you seek a Synthetic grade you need to check recommendations.

On the other hand most of the mineral grades now use 15w winter SAE and SAE 30 or SAE 40; as against 20w/40 used earlier. This recent trend is possibly or largely to meet API energy efficient "donut" "starburst" category!!

An interesting study can be done to estimate theoretical life of the pump when synthetic grades are used.

1. If we rewrite the basic chemistry principle:
Density = Mass/Volume to Sp gravity = Weight/Volume.

We get some interesting values.

a) Typical synthetic grade the Sp Gr = 1.2
b) Typical Mineral oil the Sp. Gr = 0.8
c) If the volume is fixed to 1 cc
d) The work done by the pump is 50% more in the case of synthetic oils.
e) Thus the pump should be re designed to take load for synthetic oils.

2. Secondly, it is an established fact that “lubricity” as defined in purely technical terms is better for mineral oils, than for synthetic oils.

3. Thirdly, if the flow rate of the fluid is fixed in any pump, a fluid with 50% more mass (Synthetic oil) will theoretically deliver lesser quantity of the fluid.

4. Fourthly, it is an established fact that “Synthetic oil” gives longer life, due to better resistance to oxidation as compared to mineral oils.

I thus conclude, by saying that when choosing a synthetic grade over mineral oils, one has to be vigilant and monitor the oil frequently. The pump is one area we need to monitor. Synthetic oil is not a “fill and forget” type of application, in fact it can have a snowballing affect resulting in lubrication failure. In addition, if two or more lubricants are used ( as in case of separate oils for Engine and separate for Gear box, chains etc. in the instance of Yamaha above) and one of which is mineral oil, extra care has to be taken to avoid mixing/leakage.

Hussam Adeni

Larry

Synthetics are far better off than mineral oil and so is the cost (Normally 5-6 times costlier of mineral oil) .This is because synthetic 4T will have a Viscosity index of 160 and above whereas a mineral can have a viscosity index of 140 max . This clearly shows that synthetics are superior to mineral oils as the Kin Viscosity @150'C wil be 3.0 cP or more for SAE 10W -40 if its a synthetic motor oil .

Moreover synthetics run the engine cooler because lower coefficient of fluid friction and the power generated would be great.

A. I don't know of a bad cycle specific syn oil, probably the Mobil is the most common.

B. Lots of bikes seem to do OK as far as wet clutch problems when diesel oils are used. Specifically, Rotella Synthetic (OK, its only Group III) and Delvac 1 seem to do pretty well.
I wouldn't worry about the lower viscosity number being lower than reccomended when comparing synthetic oils. That is, 5W40 Delvac 1 is radically superior to Delvac 1300s 15W40 despite the greater viscsity spread (since the spread is possible via better base oils opposed to massive doses of VII in dino 5W30 and 10W40.
Also, as everyone probably knows, the cold cranking ability of an oil is not necessarily proportionate to thickness, a classic example would be Castrol 0W30 (sold as SLX in most of the world).

Oh, and I almost forgot, among the cyclists that I know, many use Mobil 1 15W50...they call it "red cap". Apparentally works well in many bikes, but disagrees with smaller number (I don't know makes and models off the top of my head).

Just to pass on some info I got from a Shell Oil Tech. Rep. - for any Cdns visiting this site. Rotella T, 0w-40, 100% Synthetic, that is sold in Canada, is apparently a group IV PAO. Retails for $29.95 for a 4 litre jug. I'm currently running it in a '95 Cirrus, 2.5L V6 and it seems to be holding up very well. I'll be putting it in my '03 Wing, once break-in is done (whenever that is).
Regards, Doug

hondas new crf250 crf 450 have seperate engine oil and tranny/clutch oil. I dont want to put MC specific oil in the engine because it doesnt involve the clutch and gears.
Are there other differences in these and auto oils? So far I'll use 15w50 M1 for engine and tranny juice for 2 stroke gearbox/clutch.

This message has been edited. Last edited by: Xburp,

Is your bike a 4 stroke model? If so then you can treat it as any 4 stroke engine, like in a car. If you also have a car (petrol engine) and patronize a particular brand of engine oil you can use the same engine oiln for your 4 stroke 250 CC Honda Motorcycle.

If your bike is a 2 stroke model, then you will need to use 2 stroke engine oil of your choice.

M H Adeni

I have used Mobil-I 15W-50 since my Yamaha FZR-750 days, used it with FZR-1000, and now the RC-45, never had any complaints, keeps my insides sparkling clean and the best part it that my valve adjustment intervals can be easily stretched. My cams look real good after 45000 hard ridden miles.

I don't know why I didn't think of this before, but if I had a bike, I would be inclined to run Redline oil in it.

Motorcycle engines are the same as motorcar engines . They all are different . Funny yes ?

One motorcar engine might do well on one oil and the other motorcar engine can tear same oil to bits . Please do not pick an oil based on HTHS alone . Pick an oil that the HTHS will still be steady with miles on the oil . That is synthetic . The true pao mixed with ester type not commonly found anylonger . Pick one that was developed for gasoline engines not one for diesels . Available to you is the Yamalube 10w-50 , Motorex 10w-50 , Motul 10w-40 , Mobil 10w-40 , Maxima , Klotz , Silkolene and Elf for 7 or 10 dollars USD . These oils have the reserve to insure you can go one full year or 8 thousand miles in your engine and protect well during storage and that is something I seldom see spoke about although highly important .

Sounds like good advice. i picked mobil 1.
On almost all 4stroke dirt bikes the engine and tranny/clutch share the same oil. Not so on the crf250x honda. they are sperate. now i need to choose a gear oil for the tranny/cluth. Honda says to use 10w40 motorcycle oil, but since it is for gears and wet clutch i would like to use a gear oil that is also compatible with the wet multi-plate clutch (possibly no friction mods ?? to let it slip or cause varnish).Which gear oil is that??????
BTW thanks for helping

You also need to beware that Gear Oils generally are harsh on yellow metal. If your tranny spec's motor oil, gear oil may corrode the yellow metal because of high sulfur levels. I know most if all Redline gear oils are yellow metal friendly but still meeting the gear oil antiwear specifications.

Hello Xburp .

You new design motorbike engine with separate boxes will need a light gear oil for best lifetime . The industry has recognized the need for such fluids and companies make gear light 75 , 80 , 85 and 90 . The SAE grade 10w-40 is equivilant to SAE 80w AGMA in viscosity . I can recommend 85w for high heat working . If I recall , 80w is 13 centistrokes . Please see Maxima , Belray , Torco websites internet and take into consider the 10w-40 with polymers will lower to 11 centistrokes for example only . If honda wants to have minimum 11 cSt please see about 80w for 14cSt that is shear proof . May have to 85w . You situate to possible need to drain often from dusty environment just to note . Motorelo same possible from dirt .

No yellow metals in honda bike transmission . GL-5 75w-90 work but no so recommend .

HONDA CRF250X
Mobil 1 15w50 in the engine
Torco MTL 80wt in the gearbox and wet clutch.
Thanks a million for the help.

In Canada we have the excellent choice of Petro-can products. I've recently switched to Duron synthetic 5/40 for my motorcycles.

It is Jaso MA rated for Japanese motorcycle wet clutches. It has several other transmission ratings including Allison C4. These ratings are great for our motorcycle wet clutches.

Petro-can also says this oil will perform on par with their 15/40 at high temperatures.

I've been pleased with this oil. Very good quality for a reasonable price. Yes. I'm not saying this oil is better than the PAO and Ester synthetics but it is great bang for the buck and it is the highest rated oil in its weight.

http://www.petro-canada.ca/eng/prodserv/lubesgreases/9155.htm

Hi Larry,
on the information I have, Castrol recommend the following,
Engine GP 10W-40, or GPS 10W-40
Fork SYNTHETIC FORK OIL 5W
Coolant MOTORCYCLE COOLANT

Final Drive Manufacturers recommendation: REFER TO MAIN DEALER
Grease Points LM GREASE
Brake and clutch fluid RESPONSE DOT 4