Outer Limits 4x4 Board

This is just to share my limited experience with engine oils with everyone and to get some opinions.

My GQ TD42 has done about 280K and I have been using Penrite 20-60 engine oil changed at 5k intervals for the past 20K.

The price of Penrite oils has gone up a bit recently so I tried Valvoline Super diesel 15-40 which is heaps cheaper.

My oil pressure (factory gauge) has dropped slightly from where it was with the Penrite oil but my fuel economy has improved by about 1 lt/100km.

Before I used to get about 14lt/100km and now I get about 13lt/100km.
Also it hasn't used any oil in the past 5000k whereas before it would use about half a litre.

My next oil change is due and I'm going to try Castrol RX Super to see if there is any difference.

What do you guys reckon about this experiment?

Mel

20w imho is too thick for the cold temps down here in VIC. Your fuel economy would have improved as a result of less friction going to the thinner 15W40 oil. 15W40 is what you should be using here--RX super/RimulaX,Castrol JMAX etc are all suitable to use for the TD 42. Oil pressure will have dropped as a result of using the thinner oil.

Nick

Switching from 20-60 to 15-40 is a hell of a lot more significant than the fact that you switched brands. 20W60 will give higher oil pressure as it doesn't flow as easily and will build more pressure ahead of the pump, and it will sap mileage as it presents a higher resistance to the engine internals. Heck, I bet the reduced load the 15W40 puts on the oil pump alone accounts for more than a little of the difference...
The only thing that seems backwards is the change in consumption, normally a thicker oil will reduce it if it's due to a leak or worn rings or the like, though I suppose if the leak were near the area of highest oil pressure, it might be that the reduced pressure is no longer sufficient to allow the oil to escape whatever orifice it had been.

My first Oil change I did in mine was Shell 15/40. The next service was at shop and they use Penrite. I used the Shell again after that. The last one I used Valvoline. I didn't like it. The engine was noisy, with a lot more tappet noise, and the oil light took longer to turn off at start up. I'll be going back to Shell next time.

This is my first diesel, so still experimenting with it....

My little bro is a mechanic, and he recently got back from 18mths in NZ, so now I dont have to pay for mechanical work!!!!!!!!!!!!