Hi,
iv got a 351 cleveland on lpg. It has a gas research system. I just checked the oil and it was low so i need to fill it up. I have oil here its "Halvoline Multigrade-value engine protecting vehicles 1980 to 1993. 20W-50 Sg/CD"
is this ok to use with my engine? (i have 351's on petrol but not sure about LPG)
theres also "Mobil plus XHP 15W-40"
which is best and or what should i get? thanks

anyone able to help need this urgently, cheers