Different type oils and fuel consumption

Phil

I've done a similar thing to you - moving to the 10W 40 oil. I did it for the easier starting on cold mornings.

I haven't noticed any change in fuel economy by doing this. I guess it's probably because the hot viscosity (40) is the same for all these oils.

Cheers
Stephen J.

Hi Phil,

Unable to answer your question but you may be interested in my experience. 100 series TD 5 speed. On the same day I fitted a full length roof rack and started using Castrol Magnatec instead of the oil being used by Tojo dealer (dunno what it was). No other changes. Previously I had been getting a very consistent 10K per litre. Expected from the experience of others to drop about a kilometer per litre because of roof rack. In fact there was absolutely no change in fuel consumption to my astonishment. This was tested repeatedly over several tanks full so not a flukey result. This must be because of no influence from roof rack on consumption OR alternatively the change to Magnatec was worth a K per litre. I feel it is the latter and I am impressed. I am not going to stop using the Magnatec or remove the roof rack to sort it out more scientifically! Very happy with Magnatec. No conflict of interest etc.

Regards,

Mark

Hi Phil, I have been told by truckies that if they run full synthetic in the driveline all things being equel its worth 4% in improved fuel Ecomony. B ecause of the advanced technology in magatec i would believe the improvement. Wished my mechanic stocked it. Cheers Pete

Hi Phil
I have a story for you. One of my customers came back to me after a service of his Nissan Pulsar and asked "what we did to his car?"
I was concerned and questioned him and he said he was getting an extra 50 km to a tank of fuel.
My employees brother is fanatical about his car and after we serviced it he claimed he was getting better fuel economy.
We never said anything to them just did our normal service.

We used a 10w/30 mineral oil in both vehicles. Both were Nissan Pulsars around the 1996 range.
We were previously using a 15w/40 oil in them.

120scruiser

I always remember what a friend told me who raced in formula ford.
Those cars are so evenly matched, any little advantage counts.
Friend changed from the standard 30 grade racing oil used by every one else to a special light grade oil of about 10w.
Reckon it was worth about an extra 300 rpm on the straight, enough to make a difference. Always reckoned it took about 4 hp to turn the oil pump.
He used to rebuild the engine every 2nd race, so he checked every out anyway.

We ran a 1969 XWGT up on a dyno one day using new Valvoline XLD and then did an oil change with Castrol GP50 an oil specialy formulated for big bore V8's and picked up around 10 HP more.

Phil
Oil manufacturers do claim small fuel efficiency improvements with synthetic oils, as they have done with locomotives going to multigrade 15W40 from SAE40.

I think viscosity selection is one of the most important characteristics of an oil, and believe there is a fine balancing act between efficiency with a light viscosity oil and engine protection. High loads and high ambient temperatures are more demanding on oil, so you need a higher viscosity. The synthetics seem to provide this...but I have noticed that valve tapper noise is less apparent when running a slightly higher viscosity than recommended.

Modern engines run finer clearances between ring and liner, but I suspect that if valve noise is more apparent, there will be more wear in this area, so I will sacrifice the small fuel efficiency benefit in favour of peace of mind...especially with QLD mid 40s during summer.

Regards
Brid

Thanks everyone. It seems that it is worth trying. Even a small improvement in fuel economy will pay the difference in oil cost.

Phil I