Magnatec is one of the cheaper oils; you are simply paying a bit more because of the advertising. Ironically all oils cling to metal surfaces, one of the worst under testing is Magnatec! Castrol do a good synthetic
, its called Edge and will cost you about £50 - 60 per gallon.
The general problem with Renaults is that the dealers and the owners tend to put in poorer oils which just aren't upto the job, nevermind extended
change intervals. Hence all the bad rep and engine Problems. Top quality
is cheap insurance. It is made by the likes of AMsoil and Motul etc. Real synthetic
costs £50 - £60 per gallon and will happily do the extended
change intervals. Amsoil have some oils that will do 35K miles +. But you must pay a premium price for such quality.
The savings with using a real synthetic (not the stuff in Halfrauds) are 2-8% more MPG easier starting quicker warm ups therfore less emissions and less pumping losses which translate into less heat and a cooler running engine. Side benifits are overall lower emissions, better
valve condition and better protection.
You need to understand that with oils you are not comparing like with like. Real synthetic oils are between 3-5+ times stronger in film strength that mineral oils. This allows you to run a thinner
with more bearing protection than the thicker mineral oils. The thinner synthetic oils will also get to the bearings faster on start up and in particular the
bearings. On the spooling down side (switching off) the synthetic oils will take very much more heat without damage and breakdown hence give better protection for longer and last longer.
It is a no loose situation but you must make the initial outlay first. When you realise that the
will last that much longer you will see that you save money on
changes aswell as the
paying for itself in more MPG.
grades... I'll leave that for another post.