10W40 or 10W50?

[felix barrao]

Hello.
I´m going to change the oil to the VTR. Honda recomends 10W40, that should be ok for most whether conditions, but here in Spain, ( and most in Zaragoza) we have max temps of 42ºC in summer. So, theoricaly under the same specifications, should be better 10W50 over 10W40 ( best high temperature protection).
The candidates are Castrol 10W50 power1 racing 4T and 10W40 power1 Racing 4T. Same specs, same price...

What´s your opinion?

Thanks
Félix

[Stephan]

Theory in oils has moved up a little in recent 15 or so years. While 10w50 will have better protection in high temp, 10w40 will not even reach this temp because it has better heat exchange due to better flow, and this better flow also means better protection on some engine parts and less power loss too.
Oils with lower viscosity range are also considered as more robust than wide grade oils, especially in bikes with shared gearbox, so another theory and often practise from used oil analysis say that 10w50 very quickly degrade to 10w30 or 10w40 anyway.
Just different opinion to what you can see on any oil chart, add the fact that honda recommends 10w30 for bikes and even respectively for older ones.

My opinion is, if you want better protection, stick with 10w40 but find better oil, repsol has quite broad range here, including racing applications. I wouldnt use castrol at all, but this is true personal based on nontrustworthy stories ... I use elf moto 4 road 10w40, stage 1 engine with occassional track days and lot of city traffic in summer, just changing it regurarly.

[popkat]

Marty (agent pineapple) i think is not far from you, ask him what he uses..

I'd stick with the 10/40 but stay away from the castrol power 1 racing as it's fully synthetic, a good semi synthetic will do just fine.




.

[Stephan]

Yes, I forgot oem clutch plates dont like full synt oil. There is lot of good semi oils in 10w40 anyway.

[felix barrao]

Thanks, guys.
I changed the clutch discs just after buying the bike because a bad working in the clutch system, ( the problem finnally was the slave cilynder that I changed by a Oberon ). I noticed then that the engine was like new inside, absolutely clean, with 85.000 km. ( check pictures) . Since then, I have been using semi castrol 15W50, ( changing every year) and seems to work fine, but the clutch discs tend to be sticky with cold engine first time when I insert the gear.
So, I asked to the person who I bought the VTR asking him wich oil did he use, and he used Motul. I never have liked motul anyway, but, I have decidedto try Motul 7100 10W-40. Facts are facts, It´s esther base, MA2 and API SN, higher in it´s class..
I will update if the cold engine sticking discs are solved.

Thanks to everybody for the answers.

[felix barrao]

Finally the change to Motul 10W40 didn´t help with the clutch issue, ( not an issue actually, you only have to wait about 20 seconds witht he engine running before to insert first gear...).

[fabiostar]

Finally the change to Motul 10W40 didn´t help with the clutch issue, ( not an issue actually, you only have to wait about 20 seconds witht he engine running before to insert first gear...).

both mine do that first gear thing in the morning, just start it and pump the clutch lever 2 or 3 times and its fine,

[felix barrao]

Yes, pump the clutch lever helps. I have noticed that the disc sticking is more prone to happend the day after after a hot ride.