2.7 MFI - Synthetic or Mineral based oil??

[blacklotus99]

Hi,

I am looking at a '75 2.7 Carrera MFI Euro.

I have conflicting advice about the use of synthetic oils in the 2.7 MFI.
Some wrenches have said the car will run better with a mineral based oil which is what it was designed for. Others have said it runs better on synthetic (mobil1).

Can anyone shed some light on this issue with their experience in the 2.7 (MFI)?

Cheers.

[IROC]

I think either would be perfectly fine. Ultimately, synthetic oils have properties that exceed the capabilities of non-synthetics, but these properties typically only become important under extreme operating conditions which our engines rarely see.

Having said that, I use Mobil1, but also use "extended drain intervals". I only change it once a year or every 10k kilometers - whichever comes first.

Mike

[IROC]

also...a search will turn up more info than you care to read on this subject...

[JMatta]

I ran Royal Purple in my '73 2.4 S and discovered all sorts of leaks after running the car on the track for a period of time. Went back to good old mineral base and the leaks eventually disapeared. If you change the mineral oil often enough (I change mine about every 1000 miles due to track use), I don't see an issue. Plus it's alot easier on the checkbook.

[jluetjen]

It's been said before, but the earlier synthentics tended to allow leaks around engine seals. For the last year I've been using Mobil-1 Extended Formula which contains components which cause the seals to swell just like dino-oils. The result is that most of the leaks on my engine have healed themselves.

[GrantG]

I've tried both Valvoline Racing 20W50 dino and Mobil 1 15W50 synthetic on my 2.7RS MFI motor and prefer the synthetic - no significant leaks and runs real well (a bit kinder on cold starts too with the thinner stock)