Just bought a 1976 F150 with a newer[30k] 390 in it. The original owner stated that he runs 30 weight and adds a bottle of Lucas at every oil change. I am getting ready to do an oil change and just curious what everyone here has to recommend? Should I stay with what he has been running or....? Thanks!

 

At 30K the motor should still be pretty tight, i'd stick with the PO's practice and continue to run straight 30 weight.

As for the Lucas, i really don't see the need for it in a low mileage motor but it won't hurt anything, it's all personal preference.

 

30W oil likely has not been reformulated with the lower levels of ZDDP, since it hasn't been reccomended for use in new vehicles for a long time. As such, that's a pretty safe oil to run in these older flat tappet engines.
It's a bit thick, for cold weather. The Lucas would make that even more of an issue.
Depending on your location, and the weather, 30W + Lucas could be too thick for cold starts.

 

Im in Southern Oregon so it does not get below 0. I am curious about the ZDDP? I have read about it here and elsewhere. If I switched to a 10-30 could I supplement with an additive? The PO said that the Lucas was recommended to him by his mechanic because the truck would sit for a month or more between starts. Thanks

 

Current SN (spark) rated oils have zinc levels as low as 600ppm, it's recommended you be at 1,000ppm or above for a flat tappet motor.

On the other hand current CJ (compression) rated oils have zinc levels around 1,200ppm (these are diesel oils).

So if running an SN rated oil i'd advise supplementing it with a ZDDP additive, OR, just run a CJ rated diesel oil which already contains adequate zinc levels.

Rotella and Delo are two examples of a quality diesel oil, another option is to run a racing oil like Valvoline VR1, Brad Penn or Joe Gibbs which have zinc levels around 1,500ppm.

The bottom line is to keep the zinc levels up around 1,000ppm or else your camshaft will have a much shorter lifespan.

 

If switching to a more modern multi weight oil, adding the ZDDP additive would be a good idea. Most straight weight oils haven't been reformulated, but it never hurts to check the API ratings on the container. The same goes for 20W-50 and other heavier multi-grades.

Having one sit for a while between starts, the Lucas isn't a bad idea. That stuff tends to possess great cling properties.