joz8968

iTrader: (13)

Tizer

Ok, you boys have got me worried now I was just about to get my car back on the road after few weeks of upgrading but now shes parked up until I figure out what oil to put in. Im getting shot of the mobile 1 0w 40 like you suggested but should I put in mobile 1 10w 40 semi synthetic or 15 50 fully synthetic? im running decat 255 pump with the intent of adding a scot t polar performance chip in the next few weeks should I use 15 50 because of the increase in boost / heat?

joz8968

iTrader: (13)

You'll be okay on either.

If you drive hard and often, I'd be inclined to stick in 15W-50.

Rally fan 555

iTrader: (7)

Just put Mobil 1 15w 50 in mine, bought in Halfords and I think the only one not on offer and sold in a 4 lt container, fully synth branded as "Motorsport Formula"

Ash burton

Whats your feelings on vw's quantum platium 5w40 it seems quite good on the tin and i can aquire it on the cheap (i work for vw)
forgot to ad : 95 wrx auto about 80'000miles

Tizer

I use the car for fun so it sees a lot of full throttle. My local Halfords sells 5L mobile 1 15w 50 Motorsport Formula for £38 and 10w40 is on offer for £20 but 15w 50 sounds safer for my hard driving

joz8968

iTrader: (13)

An additional £18 spread over at least c.3000-6000miles (depending on how often you like to change) is hardly a sacrifice if it means you're protecting the engine more!

happydude303

iTrader: (1)

ive been using 10w 60 castrol for two years now in my forged engine running good power as well and its fine and 10-50 will be fine and if standard power then 10-40 is fine to i think jusdt stick to what you know

The Rig

iTrader: (13)

Right guys, dragging this topic out the depths of the dustbin lol

So,My question is, from data given on this topic.......

standard engine seems to favour 10/40 (slightly thick when cold cranking, not too thick or thin when hot)

modified cars seem to favour 15/50, heres my question, why does a modified car require thicker oil for cold cranking ? and am i right in thinking the thicker oil at high temp is to help aid the extra power to be cooled ? and as it is cooling more, wont go too thin like a /40 oil would ?

oilman

iTrader: (9)

Great thread resurrection!

A modified car does not require a thicker oil for cold cranking, it uses the same as a non modified engine. However some modified engines do prefer a thicker oil when being used hard and this is down to a few factors such as temps, fuel dilution etc.

So an ideal world be say a 5w-50 instead of a 15w-50 and these are available, however the viscosity gap in a 5w-50 is very large and has to be propped up by viscosity index improvers and these get broken down (shearing). So, a 15w-50 under hard use is less prone to shearing down then a 5w-50.

For heat transfer, in theory a thinner oil is best as it can absorb and lose heat quicker than a thicker oil, it will also move around the oil cooling system faster.

Cheers

Guy