Dion Chandler replied:

Brett, there is no quick and easy answer to this. There will be some specific answers for specific vehicles. For instance, in the engine, you cannot use the same oil that you would have used in the older 3.1TDI Jackaroo as what is required in the newer 3.0TDI Jackaroo. Then again this statement with particular to the Jackaroo Diesels, the ambient temps that the vehicle will generally operate in also needs to be taken into consideration.
Brett, so that others can perhaps give a more informed reply, is there a particular vehicle you need to know about, and are you inclined to buy only one or two particular brands of oil, or don't care, so long as it is suitable for your requirements.
Cheers,
Dion

Brett replied:

Thanks for the reply Dion.

Sorry I was a little ambiguous in my question.
I have a HJ75 with 275k on the clock. The engine is in good operating order.
I have always used Caltex Delo SAE30w and as far as I can tell the engine has not sufferred in any way due to this oil being used.

Several people I have spoken to recently have changed to Penrite oil and have claimed that their engines are running smoother. I think they are using a multi grade oil and I don't know what grade. It is not that I want to change oil brands but if I can used something which is more likley to reduce the rate of engine wear well why not.

Afew years ago I had a heavy vehicle with a 350 hp cummins and found via oil sampling tests that
the length of the 15 w 40 mltigrade oil's life was unpredictable from a driver's perspective and that wear rates varied considerably at the same service intervals with the only real variable was the load the engine was under during the service period and whether the vehicle was driven in the City more than on the open road etc.

Sometimes the report came back thet the oil was stuffed and other reports came back indicating that the oil was still servicable.

I then swapped over to a 30w mono grade and apart from the fact that the Jacobs engine brake worked better than ever before I could not tell that I was using different oil. One day I noticed that the oil pressure at idle was lower thatn normal(12psi) so I went top the repairer who performed several tests and at the same time we changed the oil and sent the sample for analysis. Amongst other things the report indicated that the oil was nearing the end of it's servicable life, and the truck with the new oil was back to normal operating pressures.

From then on I was able to tell by looking at the oilpressure gauge whether the engine was near to requiring a service and this always seemed to happen somewhere between 5000 and 7000km.

I asked an oil technician about this and he explained that multigrade oil changes viscosity at different temperatures via the stringing together of additives or something like that and that after heavy use the ability of these threads to string together becomes reduced and you end up with a heap of oil at the lower grade with out the ability to thichen to the upper grade. This happens over a longerperiod of time and is dependant on load conditions of the engine.
As for the Mono oil it appeard that it wors well and then deteriorates quickly once when it gets to a particular limit.

So I was wondering if anyone else out there has noticed any difference in any type of engine performance after changing oil brands or grades.

I just want to look after my old girl as best as I can.


Sorry abou the long post....