economy versus viscosity ?

[Shannow]

Bought the Navara Turbodiesel.

It came with a 10W-30 dino (supposedly 9.9cst). Achieved 10.9km/l.

Changed to DeloCXJ dino 15W-40 (15.8cst), and it dropped to 10.25km/l.

At 10,000km, changed to Mobil 1 0W-40 (14.3cst), and it regained a fair bit to 10.7km/l.

For the 20,000 km service, Castrol FormulaR 0W-40 (appears to be BP visco 70000, and a proper synthetic) with 12.9cst. Reasoning being that the manual has 10W-30 for temperatures below ours, 15W-40 above, soe a really light 40 would be it. It also had the same HTHS and pourpoint of the (somewhat) thicker M1 0W-40.

1,100km into the OCI, and mileage is just under 10.4km/l.

Waiting to see how the next 9000km pan out, but am atarting to wonder how closely mileage related to viscosity.

 

[Al]

I think in general a grade heavier will give you a max of 3% gains from what I have read. That is with fleet milage and its likely your numbers may be statistically not as accurate-due to the small sampling population-one vehicle

). Also you get some gains from going from a 10W-XX vs a 0W-XX. So to me your numbers are logical at least.

 

[Shannow]

Al,
the accuracy, I'm not too worried about.

With the turbodiesel mileage, and the fact that I'm stuck with Caltex fuels (by nature of the lease), and a single Caltex diesel pump within 30 miles of home (basically brings the error per OCI down to 1:900).

Was suprised at where the very light 40 wieight put me.

 

[Motorbike]

Viscosity at lower oil temps comes into play .

More info can be found on the Elf website and Googling concerning the older TU3MH bench test that has been superceded to the newer and much more demanding ACEA TU5JP which relates to oxidative thickening at 40c concerning A5 , A3 and 98 oils and how it relates to fuel mileage over the course of an oil change interval .

 

[Shannow]

quote:

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Originally posted by Motorbike:
Viscosity at lower oil temps comes into play .

More info can be found on the Elf website and Googling concerning the older TU3MH bench test that has been superceded to the newer and much more demanding ACEA TU5JP which relates to oxidative thickening at 40c concerning A5 , A3 and 98 oils and how it relates to fuel mileage over the course of an oil change interval .

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I'll have a look, but it's getting warmer, so I woudl expect operating viscosity to be less than it was when running the slightly thicker 0W-40.