B gearbox/LSD questions

[Super-DA9]

I would think this G70 is similar stuff and if others are using the full 125ml tube I think I still have some leeway.

G70 is not the same as ford/Penrite friction modifier. G70 is a type of friction mod designed to help make shifts better in old gearboxes but it also reduces the clunking in clutch diffs. It is 100% safe to use as it's a gearbox AND diff additive. It does not compomise the function of your synchros like ford/Penrite friction modifier does.

My only problem with the pro gear is that its fully synthetic, for a clutch type a mineral oil is best. But I may have to

I don't see why using synthetic oil with a clutch diff is bad, a lot of oils specifically designed for clutch diffs are synthetic. I'm not an expert on the subject but I have been using this combo on the street and track for the last year and it's fine.