99GTvert

I run motorcraft synthetic blend in the 99. It has not been even close to 5k miles since the last oil change, however the last time it was done was late last year, and I think its time to change it now.

I have some fresh oil & a new filter to change it today but I was wondering about a "rule of thumb": Without heavy stop and go conditions, typical oil life for a synthetic blend might be good beyond 5k miles, but what about in terms of time? On a vehicle not driven that often (meaning not accumulating many miles), would that oil be OK for 5 to 6 months between changes? Or more?

Also, synthetics have longer intervals but by how much?

Snakebite64

I change mine every spring and it (the oil) has approximately 600-800 miles worth of wear. I have been doing this for 25 years and have not had any problems. Oh Mobil 1 or RP

6-Speed

My Mustang doesn't rack up many miles so I change the oil (synthetic) once a year ... in the spring. When I changed the oil last week, it had only 880 miles on it.

SD 197

Recommended yearly change regardless of miles.

Unleashedbeast

Syn blends and conventional oils - 6 month intervals, or 7,500 miles

Refined petroleum synthetics (Mobil 1, Castrol, etc) - 12 months or 10,000 miles

True synthetics (Red Line, Royal Purple) - 12 months or 10,000 -12,000 miles

True synthetics (Amsoil SS, Mobil EP) - 12 months or 15,000 miles *I have done 18 months before on a low mileage interval with no ill effects on the UOA*

mustangman02232

say no to RP 04 cobra with 12k and oil changed ever 2k


gassers get valvoline blend 530 or 1030 once a year or 5k
diesels get 540 Shell rotella syn

allways use factory filters

Unleashedbeast

Have any better pictures of your oil pan? That looks like moisture contamination in the oil.

94Blk5.0

^ That, and who knows if it was running pig rich...

Unleashedbeast

Possible fuel dilution if true.

04goat

i run 20-50 rp in my modded ls1. being cammed i wanted the extra lubricity it has.it is full synthetic. and it see's 7000rpm each time it goes out.