Leaded Fuel?

[austin69911s]

Does anyone use lead substitute for their early 911S? Any comments or suggestions regarding this issue? I've been using high octane fuel with no lead substitute so far...

[ttweed]

No reason to use anything but premium unleaded in an early S unless you've jacked the compression ratio.

TT

[Chuck Miller]

I used to use a little lead now and then, more as a lubricant... just to keep the top end happy.

Now I just put about 1/2 pint of Marvel Mystery Oil in both gas and oil about every 6 weeks or so ... and that's all.

[austin69911s]

Sounds good! Thanks for the words of wisdom.

[Zeke]

Originally posted by Chuck Miller
I used to use a little lead now and then, more as a lubricant... just to keep the top end happy.

Now I just put about 1/2 pint of Marvel Mystery Oil in both gas and oil about every 6 weeks or so ... and that's all.

To each his own. Chuck, you're a great guy and you joined me up here at the Registry, so I'm not dissing you. I just don't see the need for any oil in the gas, it just fouls the plugs and creats carbon. And, I don't see any oil in the oil. Today's oil is much better at staying off the internal surfaces and in suspension. Besides, your engine is brand new!

I have put some race gas in my S along with pump gas. It ran fine and the lead doesn't hurt anything on an early car. That's the only way I know to get lead, is in race gas. Lead substitutes are marginal from what I hear.

[Steve@Rennsport]

Hi:

Since this subject is near and dear to me as this is what we do, I'd like to offer some comments as I've seen a LOT of 911 engine internals over the past 27+ years.

Leaded fuels are necessary evils for cars with compression ratios over 11:1 as unleaded race gas becomes marginal under hot conditions. These gasolines really do make an internal mess, however most engines that require this are race motors which are routinely disassembled & freshened up every few years so its not as big an issue as it is in street cars that run for over 100K miles before disassembly.

BA was right on when he wrote that the '72-on 911's came with very hard valve seats that didn't need any lead. I've never seen any valve seat recession in these cars, even when operated at high RPM for extended periods of time.

The vast majority of octane boosters and lead substitutes leave a mess all over the plugs, valves, and piston crowns and there is really no need to use them. That said, I do strongly recommend the use of fuel additives like Techron and LubroMoly to keep the valves and fuel injectors clean.

LOL,..I've only used Marvel Mystery oil in engines that REALLY needed that to prevent valve guide sticking (using heavily leaded aviation fuels); Lycoming 0-320, O-360 and IO-360 engines. Under those conditions, the additional mess from MM oil, was masked by the major-league lead deposits,...


Finally, if one uses good oils such as Valvoline, Kendall, and Mobil 1, oil additives simply create more problems than they solve. These oils (and a few others) do a fine job of protecting these engines at RPM's up to 9K under some very hard use.


Just my opinion though,...

[pwd72s]

Steve, your opinion is valued highly by me!

[sundaypunch]

Originally posted by pwd72s
Steve, your opinion is valued highly by me!

Amen.

How often would you recommend using an additive like Techron in an early 911? Also, what would your recommendation be for a "regular" non P-car daily driver?

Thanks

[Steve@Rennsport]

Hi Paul:

Why thank you kind Sir for your confidence.



Sunday Punch:

I use Techron every 5000 miles in all my cars (911 & others) and this maintains peak drivability.

There are lots of good non-Pcars for daily drivers and I've always been kinda partial to as assortment of VW's since my last three endured over 200K miles each with my usage and maintenance regimen.

[jayzoll]

Steve--is Rennsports Systems really at 6416 SW 33rd Place? I live right around the corner on Illinois, but haven't seen any Porsche activity on 33rd (I may have seen an orange 912 across the street once). I drive a red '73 S Targa. Wave if you see me around and we can talk cars.