1988 SM465 oil

[iamdave0887]

According to the Amsoil catalog my 1988 SM465 calls for 5w-30 Transmission Oil. That sounds awful thin for that trans. I know the older SM465's used 80w-90 gear oil.

Exactly what does this trans take for oil?

Thanks guys

- Dave

 

[Wrecker]

30 weight engine oil has the same kinematic/saybolt viscosity as 80-85 weight gear oil. Either should be fine, the 5w-30 will provide better cold operation in the winter.

 

[just a number]

any idea of when they changed viscosity?

 

[iamdave0887]

So i'd be ok with the 5w-30. it's a transmission oil according to the Amsoil catalog. This truck's primary use will be in the winter.

Would it be a good idea to swap the fluid to 80w-90 in the spring time until say the end of summer and then go back to the 5w-30 transmission oil, or just run the 5w-30 transmission oil year round?

 

[Wrecker]

Running the 5w-30 year round will be fine, your choice of course.