15w40 or 10w40

[Andyvalver]

Which is best for the f7p engine? I give my car a dailly thrashing too

I currently use 15w40

[Lunner]

i've used 10w40 shell helix

and 10w50 silkoline pro s race oil

Silkoline defo keeps tghe temps down a bit better initially, but doesn't last, haven't noticed a differnece in running between the 2, on the lookout for some 15w50 to try.

At the end of ther day its what suits your car

[Andyvalver]

Yours isnt f7p is it? Good advise anyhow :P

[VIPERONE]

10 40 is good 15 50 is a tad thick...but will still suffice, just take a few just take a few more minutes to warm up, to alter the viscosity of the oil

[Andyvalver]

So 15w50 is better for winter and for thrashing?

[Lunner]

Viscous means thick, it starst off thinck and becomes thicker, ie loosing viscosity

[VIPERONE]

the viscosity of the oil is the thickness. heat alters this variable to make the oil thin, hence when you first start your car up the oil is thicker, and pressure is high, as it warms it thins reducing pressure, :- thats why you shouldnt rag an engine form cold.

[Andyvalver]

Surely you want oil to stay not too thick but not too thin like water? Also thicker oil is better for hot running engines?

[Lunner]

:D

[matty]

If you check posts from Oilman on other forums, doubt you need a 50 grade oil. Even some exotica doen't need oil that high temp rated according to him and he lives/breathes oil.

What is more important is the lower rating for cold start protection. a 10 or 15w won't give as good protection from cold which is where most damage is done. I've used 0w40 Castrol RS which I found to work really well. Now using 5w40 Silkolene Pro S. Last oil I used was Mobil 1 Motorsport 15w50 which I found to be worst oil I have used. There was no way I was gonna risk using that in Winter.

If you want some 15w50 Lunner have about 6 litres spare.