I would like to ask if anyone {off the top of their head} would know which of common 20W50 oils have the highest viscosities at normal running temps.
The reason I ask such a "off the wall" question is because I just bought a '90 Mustang GT with 177K miles. The oil pressure is a bit too low and I figure a heavier weight oil might bring up the pressure. I know it's a band aid at best, I would just like to put off a motor swap for as long as I can. Thing runs great except for the oil pressure.
It also uses {and leaks} a bit of oil. Bout a quart or two in 3K miles depending on how it's driven, so I would like to run a dino oil for economy. I would change it in the 3-4K range.
How bout it? I'm thinking Castrol. Any help would be greatly appreciated.