Petrol Additives

Since the demise of leaded petrol, the classic car community has had to either spend loads of dosh on having the cylinder head converted to unleaded, or use bottles of additive to provide the necessary valve seat protection. Fortunately the Federation of British Historic Vehicle Clubs (FBHVC) did loads of testing of these different formulas and I chose to use Superblend Zero Lead 2000 as it was the best performing additive in the tests.
Some time ago, I bought a good batch of this additive on eBay and recently found that I was coming the the end of my bottle. As far as I could find on the internet, Superblend is now produced by Morris Lubricants and they call it SuperClean Zero Lead 2005. A quick phone call confirmed that the receipe had changed although they did say that it did not alter the valve seat protection offered. To me however, a change is a change and therefore it should be retested. A quick look on the FBHVC website and it didn't appear to be in their list of approved products.
I posted a topic on the P6 Rover Owners Club (P6ROC) website forum, and was told about the TetraBoost additive that recreates proper leaded petrol. This stuff is proper Tetra ethyl lead, which is added to the tank at fill up time. Not only am I now getting proper valve seat protection, but an octane boost to boot. By adding this product to SuperUnleaded (99 Octane stuff from Tesco or Shell), I end up with 101 octane leaded fuel. That is better than the original 5 star petrol that my car was built for and not seen since the 70's!
I took her out for a spin after filling up and within a few hundred yards the tone of the engine changed, all the rough running that I'd spent years with balancers and colourtune kits trying to get rid of just disappeared! She had become more responsive and I had a grin from ear to ear driving my old Rover up and down the dual carriageway.
BTW TetraBoost is approved by the FBHVC for recreating leaded petrol. As far as I'm concerned, it's the only thing to use. It is a bit more expensive as it adds about 14p per litre to the cost of refueling, however, when balanced against how many miles are driven in a classic car, it is well worth the almost negligable expense. For me, it adds about £25 per year to the fuel cost over 1000 miles.