Just purchased tr6 what type gas should i use and do i need gas additives because of no lesd in gas anymore

If it hasn't been converted to unleaded it is best to use a lead replacement and octane booster combined, you can then use normal unleaded fuel don't bother with these put a piece of lead in your tank or in the fuel line products, they are proven ineffective.

Medium Grade should be fine. Use Sea Foam additive with every full tank of gas.

Not sure above answers are optimum. Recommend consulting TR6 Forum at https://www.triumphexp.com/phorum/read.php?17,1042083 for straight scoop on TR6 needs re. fuel/lead/octane