Hi all,

Due an oil change and after reading all the threads on the forum I'm thinking of going the Shell Helix route at somehting like 5w/40 for the winter.

But do I go full or semi synthetic? Whats the difference other than price

 

BTTT

 

Someone must know? Whats the difference between semi and fully synthetic?

 

ask Oilman ...he will know for sure !

 

I have used full synthetics in my Subarus and fully recommend them.

 

A lot of people have problems with fully syn as it is too thin.
Castrol Syntrax is a good semi-syn oil that I have never had any problems with. In one case, it actually got rid of a synchro crunch!
You can get the stuff either from ebay or halfords.

 

I guess it's down to how you use your car. Over ten years and 4 Subaru's, 2 Legacy RS turbos, 1 Impreza 2WD and 1 Impreza AWD, I have had no problems running sythetics in both the engine and gearbox/diffs etc. I have recently returned to Subaru after an unbelieveable 12 months with a VW Golf, what a load of rubbish that was. I now have a 2003 Impreza RX auto (Wifey can't drive a manual).

 

Fully synth will retain it's effectiveness longer... Only reason to not use fully synth is if you're a) running in a new engine (when you want the piston rings to bed in properly) or b) not doing many miles between services (in which case the oil won't have time to degrade significantly)..

Reasons to go fully synth include modding your engine to greatly increase the power and running the car to it's limits - i.e. trackdays etc. Both will tend to expose the oil to higher temperatures.

As your car/engine should be well run in, try...

Miller CFS 10/40 or 10/60 if you're doing trackdays or use it very hard.
Motul 300V 15/50

I've used Shell Helix Ultra 5/40 in the past. Currently, I'm running Motul 300V 15/50 and I have 5 litres of CFS 10/40 in the garage.

Prices from AS Performance are quite reasonable.

J.

 

Slightly off the mark, synthetics are not too thin, a semi 75w-90 is the same viscoity as a synthetic 75w-90.

The problem is they can be too slippy for the synchromesh sometimes, and these are usually the high ester based ones. In a way they are too higher quality for the synchro and the use of a mineral semi being more grippy tends to solve the problem.

We find that pre sort of 98 models are happier on semi and post 98 are find on synthetic.

Cheers

Guy.

 

Sorry to jump in on the thread.
I drive my99 type-r very hard,
Which would you recomend, my oil and filter change is due next month (I do it every 3 months) I do about 3000 miles in that time
Miller CFS 10/40
Miller CFS 10/60
Motul 300V 15/50
Remember the next 3 months are going to be alot colder thn the past few...

Cheers

 

None of the above....

Motul 300v 5w-50 or the Silkolene Pro S 5w-40 would be my choice.

Cheers

Guy.

 

Why would that be? the cold weather or the way its driven?

 

5w-40 is ideal for tis time of year, good cold crank protection iand if you go for a good synthetic then plenty good enough for some hard use.

Cheers

Guy.

 

Sweet then, where can i buy some Motul 300v 5w-40 from for my next oil change?

 

from oilman pmsl

 

Kool. price then plz