15w-40 in summer and 10w-30 in winter
15w/40 - recommended 10w/30 - satisfactory
15w40 is thicker at all temps vs 10w30.
The recommended oil for a Ford 300 is Shell Rotella 15w-40. If cost is an issue, regular 10w-30 or 10w-40 oil can be used.
This should be fine, although in very cold weather you might have a little more difficulty starting the engine because 15W 40 oil is thicker than 10W 40.
15w 40 is recommended for this size engine. 10w 40 will suffice if no 15w is available.
No
The main difference between 10W-40 oil and 15W-40 oil is that 15W-40 oil has a higher viscosity than 10W-40 oil. 10W-40 oil allows the engine to run freely.
10w/30 10w/40 in -5 to 100 degree ambient temperature 10w/50 15w/40 15w/50 20w/40 20w/50 in 15 to over a 100 degrees ambient temperature 5w/20 5w/30 5w/40 below 0 degrees ambient temperature all stats come from original factory maintenance handbook for jaguar xj6
10w/40 or 15w/40 should do the trick.
Suzuki recommends the use of SUKUZI PERFORMANCE 4 MOTOR OIL, or an oil which is rated SF or SG under the API classification system. The viscosity should be SAE 10w-40 if a 10w-40 isn't avalible 10w-30, 10w-50, 15w40, 15w-50, 20w-50 can be used depending on the temprature. I would stick to 10/15w 40/50 to be safe.
I like to run 15w-40 rotella or dello or 10w-30