I’ve got a can of castrol gps that’s half full and a new can of castrol gps power 1 - which is an improved version of the old gps (with ‘power 1’ added to the name to indicate the improved formula) - there shouldn’t be any harm in mixing the old version (which I don’t want to waste) with the new should there? They are exactly the same grade and rating etc and the same ruby red colour.
Thanks in advance for any advice 
It won’t make the slightest bit of difference. If it’s the same grade oil then there will be next to no difference between the two.
Cheers rusty! I’m probably being a bit over pedantic - nice to get a second opinion - thanks.
If it’s a fifty/fifty mix, I assume it will only be “Plus 1/2”?
And if one was Semi and one was fully? :P:D
I thought I had this sorted! I’m getting confused again now!. . .;)
It would become 3/4.
Sid, don’t worry. Looks like you have two compatible oils with just a slight change of additives. (Even that might be a change of advertising.)
I’d just bung them in the same can and give them a shake, but if you want to check properly, your choice, go on line to the oil co’s site and look them up, or give them a call.
Cheers oldguy - yep your right - I’m sure the marketing dept. had a bigger hand in this than the chemical engineers who design the stuff - they’ve probably tweaked it slightly that’s all. ;)
