Hi there, I am after some advice, on my previous vehicles with automatic transmissions and before they went for a Gearbox Oil and filter service i added the Forte Automatic Transmission Treatment (please See Image) and always found the Forte products work well, my RR is in for a Gearbox service next week and the Forte rep has advised to add a tube of treatment a few days before the service, the question i have is there a way of adding this treatment from the engine bay, there is a tube which does look like some sort of breather but unsure if this gearbox related or maybe the diff! (Please see 2nd image).

Any advice would be much appreciated.

I will discuss with the guys who are going to complete the service as well but was hoping to add the fluid this evening.

Simple answer - no.

I really must change my transmission oil and filter too, but it's a job I keep putting off. I'll do the transfer and diff. oil at the same time whilst it's on the ramps.

Have a look on YouTube for a video on how to add fluid BTW . . .

The only way of getting any treatment in to the gearbox (other than during a megaflush) is via the filler port on the side of the gearbox itself.

My preference is to just have a megaflush done and not bother with the traditional drain and refill approach. The flush replaces all of the oil (the drain and refill doesn't) and the filter doesn't appear to be that big a deal if not done (the megaflush takes out whatever is in the oil anyway). 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed