I don't, as I said before I go with what the manual says and most of the time that ends up as 5W30 or 10W30, I don't think I have ever used anything else.

I would stick with a 30-weight (0W-30, 5W-30, 10W-30) HDEO. If you're in a hot climate, I would consider using a 15W-40 HDEO instead. See Chrysler Oil Recommendations.

There is no reason that you could not use a 0W-30 engine oil, even in Furnace Creek. Generally, the 0W grades are synthetics and naturally have a low viscosity in cold temperatures. However, they also have a high viscosity index which means that they don't thin out as quickly with high temperatures. In the USA, Chevron Delo 400 Synthetic would probably be the easiest 0W-30 to obtain.

Oil, That is a deep subject. Synthetic V conventional, To start with they BOTH start out using the same base stock (dino juice) It is all in the additive package. Conventional motor oils of today are so much better than they were even 10 years ago. If you run a good quality oil with weights proper for the clearances in your engine you should be fine. Change often. The use of synthetics has some advantages but to get the most out of synthetic oil you would want to run extended oil changes, which would be fine in a new tight engine. But not for an engine that has 100k plus miles and 30 plus years old. too much blow by and other combustion contaminants. (Coolant, dirt, built up sludge, ect). These engines were designed for a thick oil film. Probably no thinner than 10W30 but probably a good 10W40 or 15W40 for summer. But use what ever works for you just use a good oil (synthetic or conventional) and change often use a good oil filter. (stay away from those orange filters JUNK if you don't believe me just cut one open)
Just my $.02 worth, take it for what it is worth.

Cliff N

_________________
This is my hooptie, there are many like it but this one is mine. With out my hooptie I am walking and without me my hooptie is broken down.
1980 dodge d150, sl6, 4sp od, air

i use valvoline premiun blue 15/40 diesel oil i just love that stuff on my 72 duster and other non diesel vehicles,give it a try.. JASON

Lubriplate Super GPO heavy duty motor oil. straight 30 warm weather, 10w30 cold weather. contains ZDDP. not cheap but good stuff.

andy.

_________________
84 D100 /6 long rod 225
86 D100 /6 my sons w/offy intake/weber carb
2016 buick regal turbo

I looked up Lubriplate Super GPO heavy duty motor oil and the MSDS lists the oil component as "Solvent Dewaxed Heavy Paraffinic Distilllates". That suggests to me that this oil uses a Group I base stock, which is similar to the solvent-refined oils that were available back in the '60s and '70s. The better engine oils (Group II or III) have "hydroprocessed" (or something similar) in the description.

If Lubriplate Super GPO oils are expensive, I think there are probably better oils available for similar or less money.