Mixing Oil Viscosity?

[SteveSAS]

Hi guys,

I was going to put a slight mix of oil viscosity in my S3 as I had been given some so wanted to save money. However TPS said it was a bad idea, did they just want my money or do they have a point??

I had 3 litres of 5w 40 Quantum full synth (which I normally use) & mixed with 2 litres of 5w 30 full synth (Castrol Edge & Helix I believe) what issues could this cause????

Thanks

Steve

 

[aragorn]

It'll end up a bit thinner than 5w40, but i'd say it would be fine.

 

[phil miller]

not ideal but not really a problem TBH, both are fully so i wouldnt worry to much

 

[FergyA3]

They will mix fine mate and you'll have a 5w 37 oil or so I've read about people using 5w 30, 5w 40 and I use 0w-30 in my A3 . Like Phil said as long as both are fully synthetic it should cause no problems.