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Read our primer articles on High Mileage Oil, Synthetic Oil and Kinematic Viscosity


I've just built a Westfield 2 seater sports car. I have fitted a Ford 2.0L Duratec Engine into the car which runs on Throttle bodies,Webcon Engine Management, lightened flywheel etc etc. I have been running it in on 10w40 mineral oil (1200 miles - 2 oil changes)and now want to change to Synthetic oil. Everyone in the UK raves about Mobil 1 so I went out yesterday and bought 5litres of Mobil 1 0w40. I am now concerned that I have the wrong oil. I have just read an article that says for fast road/race use, I should use thicker oil. Can anybody give me some advice please. If it helps, the car will only do approx 4000 miles per year but most of these will be under hard use eg Track days, etc etc. The car revs upto approx 7000 rpm but usually between 4000rpm and 6000 rpm.

Any advice gratefully accepted.


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Westfield ,

The article you speak of probably is refering to Formula 1 engines in general where they use a thinner viscosity on long tracks than on shorter tracks with many corners which place the engine under higher load when then , they choose a slightly thicker VI lube because of increased oil temps and thinning . These are dry sump engines where oil temp is closeley controlled .

If your engine is not fueling up the oil you might could go with a well built approximate 10.5 centistroke 30wt under all conditions you speak of . Some additional safety can be had with a high end 5w-40 such as Silkolene , Motul ect in that Ford engine .

Fuel loading and thinning of the oil will always be your engines worst of enemies

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