View Full Version : Gasoline additives or not?

11-22-2009, 12:17 PM
I've read pros and cons on octane boosters, in general.

What are the thoughts on TR6 specifically?
I obtain 93 octain fuel and I add 1/2 bottle
of octane booster per 6 gallons of 93 octane fuel.

My engine is stock except for a 6 into 1 exhaust header.
All my settings are Bentley Blue book.
Should I be using the octane boost or will it
eventually harm my engine?

Thanks as always,


11-22-2009, 01:06 PM
Not likely to hurt anything, just a waste of money, IMO. As long as the engine does not knock or ping under load, the fuel octane is high enough. And there is no advantage to having the fuel octane any higher than required.

Most octane boosters do almost nothing anyway, at least not at such low ratios.

11-22-2009, 01:30 PM
They drain your wallet. Put some Sea Foam or Stabil into the tank if ya need to feel like you're helping the engine.

11-22-2009, 02:24 PM
Yes, I don't think you will notice any difference it you don't add it.

11-22-2009, 02:27 PM
In fact I would quit adding it and run mid grade and see if that works

11-22-2009, 03:32 PM
We can't get 93 in Az and my TR3 runs fine on 91 even in the summer heat

11-22-2009, 03:45 PM
What about lead additive on Tr3?

11-22-2009, 04:10 PM
I use a lead additive just for insurance, not sure it's needed...lots don't use it and some have experienced recession and others have not

11-22-2009, 04:52 PM
Here's an article from the VTR (https://www.vtr.org/maintain/valve-seats.shtml) about valve seat recession. The author tends to poo-poo valve seat inserts, perhaps because many have been improperly installed. I know the guy that I brought my head to for work had some horror stories to tell of seats he installed that fell out. He went on to say, he feels that he has really licked the problem as he hasn't had an incident of a seat falling out for over six years. It was a matter of finding the right type of inserts along with the correct tooling for proper installation.

In the long run, hardened valve seats are most likely the best way to go. After all, they have to put them in all of those aluminum (and I suppose cast iron) heads that come on cars today. If they work at the OEM level, there's no reason why they can't work with a machine shop doing the job..

But, just to add, if you're not having any valve seat recession, then just keep plugging away until you have to do something about it. If there was a lead deposit there to begin with, it can last a long time.

Do the lead additives work??? That I can't answer, but from what I've read, they are lead <span style="font-weight: bold">substitutes</span>, and not the same chemical make-up of the lead that was originally in gasoline. Some supposedly work better then others, but it's not the same as the real thing.

11-22-2009, 06:03 PM
:iagree: For awhile, there were additives available that actually contained tetra-ethyl lead; but they were eventually pulled from the market.

The Brits ran a rather thorough test when they went unleaded; and found that most additives on the market did nothing to preserve valve seats. Apparently one of them even made things worse! Unfortunately, the same brands are not available in the US, so their test results aren't much help for us.

Ironically, the only time I've had trouble with valve seat recession, it was a head that had the hardened inserts! Never did figure that one out, except it may have been because I also installed 'racing' valve springs with substantially more seat pressure.

So, my advice is to not use an additive, and save the money you would have spent towards valve seat inserts. Since odds are very good that you'll never have a problem, you'll be well ahead of the game.

11-23-2009, 12:35 AM
The Brit study quoted above identified Redline Lead Substitute as an additive that reduced recession in their tests. They only suported two additives as effective and the other was not available in the US.

11-23-2009, 12:37 AM

11-23-2009, 07:17 AM
Howdy Folks,

Since I`ve moved to SC; I`ve seen quite a bit of Gas Stations supplying gas with 10% Ethanol in it. I don`t believe this is a good thing.

There is some word that the "Ethanol" may be killing our 4 &amp; 6 cyl. engines(?). Anyways; What have you folks heard, read or whatever about the "ZDDP" Oil Additive? I believe Moss offers it but I`d just like to get some opinions on adding it to the oil.

Thanx in Advance,


11-23-2009, 08:11 AM
Tetra-ethyl lead was bound to the rest of the benzine molecule in the process of making gasoline. Pouring it (or about anything else) into the tank and expecting it to "substitute" for TEL is fantasy. Stabil WILL help with the water the ethanol absorbs and extend the usefulness of the fuel a few months.

Ethanol is an evil in about anything using gasoline. Marine industry is screaming over it, many smaller four-stroke engines are being trashed from its effects. The stuff destroys seals and gaskets, if it sits in small carb passages it promotes corrosion rapidly and clogs ports. Another instance of knee-jerk reaction to perceived problems. Lunacy.

Some marinas still have access to non-ethanol fuel but that's changing. AvGas is ethanol free but unless you own a 'plane you'll play heck getting it.

Short version: Sea Foam or Stabil. That's it. The rest is snake oil.

Waste yer money on BEER instead. :thirsty:

11-23-2009, 08:33 AM
Waste yer money on BEER instead. :thirsty:

A wise man indeed. :cheers:

11-23-2009, 11:27 AM
Since I`ve moved to SC; I`ve seen quite a bit of Gas Stations supplying gas with 10% Ethanol in it. I don`t believe this is a good thing.
It's now a federal mandate; even the stations without the sticker on the pumps are mostly supplying E10.

We've been using it for a long time here in CA (ever since they decided it wasn't as bad as MTBE) and while I certainly wouldn't call it a "good thing", it hasn't been as bad as some claim. The main problem with our TRs is that it will attack original fuel pump diaphragms; so you may need to rebuild the pump with a new ethanol-resistant diaphragm if it hasn't been done in the last 10 years or so.

As far as ZDDP oil additives, there doesn't seem to be any clear consensus yet on whether they are needed for stock engines in normal usage. Here's a good article on the subject, IMO:

Note in particular the comments "Some additives marketed to increase ZDP ... may actually degrade that oil's performance." and "... except for break-in, <span style="font-style: italic">you don't need additives.</span>"

PS, Ethanol in fuel has nothing to do with ZDDP in oil; two entirely separate topics.