motor oil for old 2 stroke motorcycle

[Steevensi]

I know there are a lot of dicussions about oil you can use in your bike but this is a bit different...I think.

The bike is my vintage 1974 Suzuki TS 250.
Owner manual states to use 20w40 in the engine (transmission / motor, not the oil for mixing with the gas).

I can't find 20w40 anywhere around here.
Is it safe to replace it with 10w40, which is easily available?

From what I understand 10w40 would be thiner when engine is cold than the 20w40. What would be the effect on the clutch if any??

Thanks to all.

[salukispeed]

A bit closer to your 20-40 would be Shell Rotella 15-40 and it is wet clutch safe and has The ZDDP additive which could be good for the trans ( Opinion ) But stay away from the newer auto oils that talk about mileage and saves gas. the additives can be bad for the clutch. Does the engine have oil injection system or premix required?

[Steevensi]

It has a CCI oil injection system.
It still works great.
Thansk

[Steevensi]

A bit closer to your 20-40 would be Shell Rotella 15-40 and it is wet clutch safe and has The ZDDP additive which could be good for the trans ( Opinion ) But stay away from the newer auto oils that talk about mileage and saves gas. the additives can be bad for the clutch. Does the engine have oil injection system or premix required?

I see many type of Rotella 15w40.

the one I can have locally is the "Rotella T triple protection". But I see that , at least, the T4 and T5 are also available in 15w40.

Which one should I go for?

Thanks

[Gowing]

When I got my 75 gt750 zook 2 stroke up and running, I changed the tranny oil a couple of times with 30 weight regular modern motor oil. Non synthetic. I know I just bought some oil and the selections are like going to the yogurt section at the grocery store. So many choices!
I don't think the clutch in your two stroke touches the transmission oil, not like a four stroke.

[tlbranth]

Delo would also work. It's 15/40 and works with wet clutches. I use it in all my bikes.

[robin1731]

When I got my 75 gt750 zook 2 stroke up and running, I changed the tranny oil a couple of times with 30 weight regular modern motor oil. Non synthetic. I know I just bought some oil and the selections are like going to the yogurt section at the grocery store. So many choices!
I don't think the clutch in your two stroke touches the transmission oil, not like a four stroke.

All the two strokes I've worked on do have a wet clutch. Looking a parts fische of the OP's bike it does too. The clutch is in the same oil as the transmission. Exactly like most 4-strokes. So you need the same type of oil as, say, a Honda Gold Wing. Regular dino oil or synthetic will work. As long as it's compatable with a wet clutch.

.

[Gowing]

Sure is nice to have a professional to help us on a daily basis, thank you Robin.

[salukispeed]

My experience has been with the Rotella 15-40 T3 and it appears to be replaced with T4 and so far so good after 2 oil changes. Some here really like the T6 synthetic. . I am not ready to extend the oil change intervals that the Synthetic could allow. I am old school and like to see what the oil and filter show for particles and debris. I am sure the ( T6 ) is good oil.

[Steevensi]

I just bought the T4.
But I won't be able to try it this week as the bike's coil died on me last night on my way home...
Thanks

[Gowing]

I use the T6 synthetic in my st1300 motor. I'm sure it's fine in older two stroke trannys but I'm scared to put in my 76 goldwing or older cars. Synthetics are so slippery and clean so well, I worry about leaking seals down the road but I've read that's nonsense. Here I go talking about oil, OMG!

[Steevensi]

Yeah, I just open a can of worms.
Everybody has an opinion on oil!

[Doug Hasert]

I've used synthetic in my 1982 Goldwing many times , no problems with leaking and the clutch is fine. It is my sidecar rig and works hard.