Hello all! Questions about motor oil and Differential oil
 

Hi, I'm new to the forum. I just picked up a 1969 Plymouth GTX, numbers matching stock 440 engine, 727 torque flight trans and Dana 60 sure grip rear with 4.10:1 gears. As I'm just getting back into the classic car world I have a few questions I hope some knowledgeable MOPAR owners can help me with. I'm told to use conventional motor oil such as Castrol gtx 10w-40 with the zinc additive in this case Comp Cams for the engine. I'd really appreciate some input regarding rear end gear oil. With this particular rear do I use GL4 or is GL5 ok? and I was told no synthetics, use regular gear oil 80w-90 and a good limited slip additive. The Manual gave me part # 2933565 for a standard sure grip and #2585318 for a 9 3/4 rear, can't seem to find what the equivalent to these would be. Any help would be greatly appreciated as I want to use the correct oils. Thank you!!

My engine oil preference is Mobil 1 "10w - 30" conventional oil, as recommended by my engine builder. The GL5 differential lubricant googles up as superior and I use Lucas 85-140. This is a race only application 3400 lb. car.

Depending on where you live (Cold and Hot) Climate. 10W40 or 20W50 GTX Castrol or Mobile 1 is a good choice for the engine oil. in the stock applications. Will not hurt to add a small amount of ZPPD. But should be 100% necessary after the cam is broken in. But I dont think you need to much specialty oil.
As for an Oil Additive.... LiquiMoly is what I use.

https://www.liqui-moly.com/en/produc...additives.html


AS for the Differential Lube. I have used Torco Oils for many years with very successful results. But that's just me. :)
https://www.torcousa.com/products-auto-pro.html

For a numbers-matching '69 GTX--valuable car!--I would be looking to install a pre-oiler, even though that would be a non-stock modification. The valve lash/rod knock on the 440 in my '66 Charger, when I start it up after letting it sit for days, makes me grit my teeth, even though I know it's not an irreplaceable engine (like yours). I would be a lot more focused on cold-start engine oiling than the differential lubrication.