20w-50 for inline engine
- Thread starter JonS
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P.S. I should add that most Japanese 4s (whether water cooled or air cooled) will run just fine on either 20w50 or 10w40. There's probably not a big difference one way or the other.
Just make sure to avoid "energy conserving" oils as some of them may cause the wet clutch to slip. This is not hard to do since most of the 10w40 and 20w50 weight oils are not energy conserving. But if you run a weight typically used in modern cars like 10w30 then you're more likely to encounter friction reducing additives that your wet clutch won't like.
IMO you don't need a motorcycle specific oil as long as you avoid the energy conserving oils.
Just make sure to avoid "energy conserving" oils as some of them may cause the wet clutch to slip. This is not hard to do since most of the 10w40 and 20w50 weight oils are not energy conserving. But if you run a weight typically used in modern cars like 10w30 then you're more likely to encounter friction reducing additives that your wet clutch won't like.
IMO you don't need a motorcycle specific oil as long as you avoid the energy conserving oils.
I disagree with this statement. I have used ATF in 2 stroke gear boxes with wet clutches many times since the early 80s. Because of good clutch action over 80wt gear oils. And Auto car trannys sure don't have any wet clutch problems with 5w 20 wt. ATF.
I use a 20w 40 or a 10w 40 in all 4 stroke dirt and street bikes and ATVs myself. I think in a wet clutch 4 stroke bike, the oil should be changed often. Because of the clutch and tranny debris. Better a clean dino oil than a well used synthetic in wet clutch bikes. I would not use a oil that has moly in it like some of the newer car oils. Moly can be a problem for wet clutches. If the clutch surface area and or clutch springs are marginal. Just my 2 cents.
i used mobil1 15w50 in my 1992 honda cb750Nh. and it made the engine get very hot... and noisey. so i then went back to 10w30 mobil1 and the temps went way down. and everything was running right again... I did this about 4-5 years ago. it was a in-line 4 banger.
That's not good. I just got off the phone with a rep from a local refinery (Goa Northcoastal) and he said the 20w-50 would actually be better for my engine. He said you can always go thicker, not thinner. I am using 10w-40 Torco in my 400cc twin inline and after about 20 miles of 5000+ rpm's the head gasket starts to weep and run down the outside. I thought if i went a little thicker, this would not happen. But, i know a thicker oil tends to get hotter because of the added fricyion of being thicker. He also said the thicker oil would make my clutch react better. ????
The thicker oil will exacerbate the potential problem by making the engine run even hotter. But the thicker oil might withstand the heat better.
If it's a modern Japanese bike then 10w40 is probably better if you can find one that will withstand the heat.
I used 10w40 in my '92 GSXR-750 which was the epitome of the high RPM hot running high compression engine. It held up just fine but I changed the oil every 2k miles.
I use 20w-50 year round in my 83 Suzi' GS1100GK. Works fine.
I had many cars and bikes, but the one I consider "The Love of My Life" was a CB 400F Super Sport. 1977 model, if I recall correctly. For those who're not familiar with it, it is an air-cooled inline-4. The ONLY oil I ever used in it was Castrol GTX 20w-50. More or less, it was also 20w-50 for all my other bikes, except for rare extreme-usage applications when I had to use HD-30 Castrol. But the other bikes are not so important.......... the CB 400 Super Sport is. If 20w-50 is good enough for the CB 400 F, it is good enough for every vehicle made.
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