Imperial Car Club Forum

What's the best gas for one of these old 440s? Do they need premium? Do you have to put in a lead substitute for the really old ones?

Yes we do need to feed them a special diet. For my 413 for instance (and your 440) I need to add octane booster, lead additive, and most of all Zinc since we have the old style cam and lifters.

My engine was rebuilt at some point, so it doesn't seem to mind straight up 93 octane. There's no knocking or anything like that with mine. As gas changes from one area to the next, I would simply try using straight 93 octane and listen closely. Especially when going up a hill where the engine is struggling - if you hear it pinging/knocking then you need a little something extra to help it out.

This is common with all old engines from the early 70's and older. Won't know till you try it.

One other thing I would recommend is to get some zinc for the oil. The modern oils are not like the old ones used in these cars, and that extra zinc (and other things) will really help protect different areas of your engine. I've heard two rules of thumb - use oil designed for diesel engines (as they still have all the good stuff we want) or use any normal oil and get the additive when you do an oil change. I get mine done at the local Valvoline place and ask them to put the additive in when they are changing the oil.

I run Penn Grade oil so no need for additives and I run premium gas with nothing but marine 2 cycle(TC-W3 in it) to offset the affects of the ethanol.

Have marine gas here as well, but it's been closed lately. No other place to get pure gas unfortunately.

You can retard the timing just a little bit, and you will have no pinging or knocking, engine will last forever. A quick head upgrade will eliminate the lead additive as well. Be careful, the effects of no zinc in the oil will be slow and expensive. I am unaware of any motor oil that now has zinc in it.

I stand quite corrected! PennGrade as well as some others now DO have zinc now.

I have a case of lead additive and a case of octane booster left over from my 1969 Le Baron 440, so I have not been keeping up too well and am fixed for life on my 59 413.

Here's a good article on the topic: https://www.hemmings.com/stories/2012/1 ... er-engines

Looks like even newer diesel oils don't have enough zinc anymore. Based on the article, it looks like you want diesel oil rated at CI-4 specification. If it mentions CJ-4 as well then that's likely not going to be good enough.

From the article, you want to have about 1,200 ppm of zinc and phosphorus in whatever oil you use to help with engine starts. It seems to all come down to engine starting, not running.

Brad Penn, now Penn Grade always has and it’s all I run in my classics.