No? A guy I know does a lot of miles in his every summer, his main DD complaint is that it doesn't have a cup holder for his Tim Hortons coffee!Any halfway decent oil will suffice for the use you intend. Anything beyond a conventional 10w30 is over kill. Despite it's low miles, I would check stick before every outing. Especially because it is an aluminum block engine built by Lamborghini. I would love a ride in a classic, I couldn't own one though.
I think Edge and Mobil 1 are the only ones left that make a fully synthetic 10W-40 high mileage oil. Another good one to consider that I and a few others have brought up recently is Pennzoil Euro L 5W30. It's very thick, bordering on a thin 40 grade, has very high euro approvals as well as API SN, and seems like it would be a good fit for your engine. It has performed well in our 06 Infiniti M45's 4.6l V8 with 340 HP and I've seen results on here from someone who ran in it in a Honda 1.5T and it actually held its grade well despite a lot of fuel dilution.Okay what are Castrol's strengths? What applications are they preferred for vs. others?
Pretty sure you have this backwards. API SP oils have strict limits on ZDDP anti wear additives which makes them inferior. I would never use any API SP oil in a performance engine.And any API SP oil should be far superior to anything that went into that car when it was new.
All older cars will eventually develop oil leaks. Ultimately the only correct and long lasting solution is to replace whatever gasket/part leaks. Especially on a beautiful low mileage classic like your Viper.So far it doesn't have any serious leaks though I know there's a slight scent after driving it. I just want to do some preventative efforts.
Most cars that sit or have low mileage show some of the biggest problems. Used to be a thing for people on Sundays to do church,lunch, and a drive to get the car out and blow the stink off.It's leaking from lack of use. It's not the oil's fault.
Here's another aspect to it, in conjunction to what @OVERKILL said above.So the opinion is to use 0w-40, a starts off thinner then becomes thicker oil than stock? This would tend to help with protection and possibly be less inclined to leak than 10w30. Other than possibly reducing fuel efficiency an unmeasurable amount (which isn't a concern on this car's use) what would be the downsides (why didn't they use this originally)
Here's another aspect to it, in conjunction to what @OVERKILL said above.
If you compare 0W-40 to 5W-30, the 0W will be a bit thinner when cold (say at 40F, more so the colder it gets) compated to 5W, and the hot viscosity 40 will be thicker than the 30 when at operating temperature (say 200F). So the 0W-40 will give better cold cranking/starting (even though you probably don't drive that car in cold weather), and the 0W-40 will give more wear protection at operating temps.
0W-40 oil wasn't around 25 years ago when your Viper was made, that's why they didn't spec it.