Oil differences- does it matter?

[Roger]

Hi all. The store where I buy my oil from has always stocked the Penrite Light Diesel oil SAE 15W-40 in 20 litre drums. This is the stuff I have used since buying the MU- nearly 3 years now.

A few weeks ago I went in to get some oil and he didn't have the 15W-40 Light Diesel oil.
The bloke said they don't have it anymore and instead, had a new oil called Penrite Diesel 15. This oil is a 15W-50 rating.

As I desperately needed to change fluids, I bought it and put it in the gearbox, transfer case, and engine.

I am noticing that the oil light is taking longer to go off on first start up of the day than previously (I'm sure it is).

Is this new 15W-50 grade oil thicker than 15W-40?
Is it suitable for the 3.1 engine, g/box, t/case?

Thanks for your help.

[geeves]

Once I finaly get the janurary newsletter written there will be an artical on the science of oil that may help.Essentialy the 15w = cold viscosity and the 50 hot. Many factors affect how quick the oil light goes out including that panicy thought that somthing has changed. As long as this is a specific diesel oil with a cf or higher rating (nearly impossible to find anything else) its ok for each 5000k. As a generalisation high quality engine oils shouldnt be used in the gearbox and xfer case as the friction modifiers can interfere with the syncros causeing hard gear changes untill cheap oil of a similar grade is used. No permanant damage is caused so if its already in there and not causeing issues dont worry till next change