Is 20W-40 oil ok to use in the firestorm?

[shammi]

Hi, my 1998 firestorm is nearing its oil change and from my research online, I see people recommend 10W-40 motorcycle oil. The issue I have is where I live this type of oil is super costly. So I was wondering if it could cause any harm if I put 20W-40 motorcycle oil (CASTROL ACTIV engine oil 20W-40 (4T) to be exact) as its priced more reasonably.

p.s. Our country temperature is warm all year around averaging 35°C. We don't have a winter season here.

Thanks and have a great day

[Pete.L]

It should be fine, it's a bike specific oil.
The 5, 10,20W is only a lower temperature rating. In colder climates we need a thinner oil for cold days to help the engine turn over faster at start up, especially with a big V twin.
Try it and report back, it wont do any harm

Pete