ChrisB

If you have a choice of oils from different manufacturer's but with the same rating (ie 5W/40) is there any technical reason for choosing one brand over another?

Is Mobil 1 a better choice than Castrol GTX, Elf or [Insert Brand]? Or does it just come down to price and / or the recommendation of the car manufacturer?

Cheers,

Chris.

Pete Croney

Each manufacturer will use different ingredients and the XXw/XX number merely indicates the viscosity at various temperatures.

These incredients include detergents, friction modifiers and statically charged particles.

Most oil manufacturers are more than happy to let you know what they use and why. Speak to their technical depts, or mail them.

brickboy

FWIW I think that the full synthetics from all the major brands (Total, Elf, Fina, Shell, Esso, BP, Silkolene, Castrol, Mobil etc etc) are pretty much as good as each other in terms of lubricity, protection, life etc. The key thing is to make sure the viscosity's right (0W30 seems to be too thin) and to simply change it regularly, and especially before / after track days!

For a while I've been using Valvoline SynPower (local motor factors has it for £24 for 4 litres, quite a bit cheaper than Mobil 1) which is a 5W40 full synth. Seems to do the job very well -- no noticable consumption between changes.