Good afternoon All, I am getting ready to do an oil change on my 2014 Thunderbird Commander. The book says i can use Castrol 4t 10 40 or 10 50. What you you guys recommend? The reason i ask is for some reason the 10 50 is cheaper than the 10 40 for some reason. A 6 pack of the 10w 40 is 72 bucks and the 10w 50 is 53 bucks. Any advice you can give would be much appreciated.
Can't help I'm afraid but hopefully someone will pipe up soon enough, however from what I understand 10w50 is slightly thicker when up to temperature so if you're in hotter climates I might be tempted with that (no real knowledge though)
I would suspect that 40 viscosity is actually recommended, and I would think more like 30 is the makers' recommendation, all using higher viscosity will achieve is to slightly increase oil pressure and higher loads on the oil pump and its drive, It can be beneficial on a very high mileage engine with increased clearances and low oil pressure but on a good motor its really not needed, if you're using a synthetic oil then it will handle high temps anyway.
