Just a quick one would it be wise to use a diesel fuel treat once every month?

Personally, I never have on my TDi 100bhp and it has always run very well. But I have always used Shell V Power now Nitro + fuel in it. Some people like to use cheaper supermarket fuel and say a Millers fuel additive. It is a personal choice and I think both are OK.

I usually add two stroke oil to my diesel if I fill up a bit. Get it for free and meant to help the running of the engine, I have absolutely no idea if it does but it makes me happy inside haha.

Diesel is a heavy oil fuel so no need to lube it unless you've bought washed diesel.

 

The PD fuel system runs at such a high pressure that it's pretty much self cleaning so some cleaning agents can actually do damage to seals. For an older diesel engine, additives may help but in modern diesels they're not really needed.