Chaps,

I desperately need to know the name/viscosity of the FULLY synthetic Shell oil, and the name/viscosity of the SEMI synthetic Shell oil as I think the dealer may have used semi instead of fully

 

Shell Helix semi-synthetic is what Subaru UK recommend you use.

Fully synthetic isn't necessary, will bring some very small advantages, but unless you drive your car rediculously hard, and go the full 6 months between servicing, the benefit will be minimal!

 

from my 15K service bill

Mobil 1 5W-40 oil is the fully synthetic oil.
Dunno for the semi-synth

 

Ernie,

The fully synthetic oil that Shell supply is Helix Ultra, the semi-synthetic is called the Helix Plus.
There are others but I'm sure it would be one of the above.

Cheers,

Rob.

 

Shell retail 3 engine oils:

Shell Helix Ultra 5W-30 fully synthetic.
Shell Helix Plus 10W-40 semi synthetic.
Shell Helix Super 15W-40 mineral oil based.

Hope this helps.
BD