A friend of mine has a 1994 diesel vehicle and asked the question "will biodiesel affect the seals etc in my engine". Is there a guide as to when diesel engines became suitable to run on biodiesel without harm?

sadly no as some euro cars are stil not comatable here. Toyota's,holden(isuzu) post 98 are all good.
Remember that the seals when they fail change them to VITON then all is good. It could be fine. You could be more specific on the model to assist with people giving you advice.
WElcome to the forum.
Cheeers Nick

__________________
Cheers
Nick.

Roidio 2001 Holden Rodeo 4x4 2.8L TD. 2.5" Straight through exhaust sytem, heat exchanger shower system. 2" Body Lift,
And lots of fruit, B100 for 25,000 no problems.

Elsa 1983 Mercedes-Benz W123 300D. The Fastest Merc in Oz, Loving B100 Burgers

Thanks Nick,
I have asked my friend to be more specific and will get back to you.
He also suggested that, as a sole producer and uses all his own biodiesel he is NOT subject to the government excise - is that true?

Welcome to the site, silverfox, but you should invite your friend to join the fourm and get all his answers directly. It sounds like he will need a few answers.

Yorta is right mate, your friend should really be here too. He is incorrect on the exise issue the government should get 38.5c per litre But it isn't realy enforced too much that im aware of.
Goodluck in your endeavours

__________________
Cheers
Nick.

Roidio 2001 Holden Rodeo 4x4 2.8L TD. 2.5" Straight through exhaust sytem, heat exchanger shower system. 2" Body Lift,
And lots of fruit, B100 for 25,000 no problems.

Elsa 1983 Mercedes-Benz W123 300D. The Fastest Merc in Oz, Loving B100 Burgers