Oil Change - overfilled it

[arrow]

That seems like very good fuel economy to me, especially with the low gear and occasional low range work.

[erad]

Last week, I had to go to Canberra for the day, and filled up with fuel there (much cheaper than at home). Overall consumption for 650 km (with the extra 1 L of oil in the sump), including 350 km of rough stuff was 8.3 L/1100 km. The dashboard readout on the way home was around 7.8 L/100 km, so maybe the extra oil was causing some more drag in the engine. The dash readout of consumption is very close to what I actually get when I fill up, so maybe there has been an improvement. I have gone to 10W-40 oil instead of 15W-40 which I used over summer. I think that makes a difference, but the comment above was about overfilling the sump, rather than oil viscosity.

[nj swb]

I switched the oil from 15W-40 to 10W-40, and I was hoping for slightly better consumption. Time will tell...

The first number is the cold viscosity, relevant during start-up (how quickly oil pumps to where it's needed). The second number is the warm viscosity, which is the one that will have most impact on economy during normal running.

During normal running, you've changed from a 40 weight oil to a 40 weight oil.

[erad]

Yes NJ - I think you're right with that. The problem here is that in winter, it is COLD. Damn - I am sure it is getting colder! I reckon there would be at least a 40 Deg C difference in oil temp between summer and winter, and therefore the oil viscosity at operating temperature in winter will be slightly higher for the 15W-40 oil. Probably not that much difference, but I will use the 10W-40 through this winter and then replace it with 15W-40 for summer because I will most likely be towing my caravan in both seasons for probably 40% of the time. I don't like the idea of 10W-40 for a really hot day, towing my caravan.