Garyss

In a 1974 2.0 914 should I be using Castrol 20/50 gtx or would it be better to use Mobil 1 15/50 synthetic
engine just rebuilt have done break inn with Castrol 20/50

Dr. 914

no synthetic!!!!!!! use castrol 20/50 in the winter and straight 40 in the summer, get an oil with zinc in it and you will be all set

Garyss

Thank you you know my car it’s the LE that you helped me with.

Garyss

Should oil then be changed every 3000 miles or once a year what ever comes first

Garyss

What brand 20/50 is the best
what brand straight 40 is the best
to be use on the 1974 2.0 motor one the 914

Petza914

I used Mobil 1 15W/50 full synthetic in my 914 for years. For the past 5 or so, I've been using Driven DT50 15W/50 full synthetic without any issues. The Driven oil is good to 300 degrees F and is very high in both Zinc & Phosphorous (over 1,000 PMM even in UOA) and Moly. Not going to change a winning game at this point.

For someone concerned about using full synthetic who wants a blend, another good choice would be Driven GP1 - I ran some of this in my '79 928 when looking for a lower cost oil than the DT50 to run for a few changes with SeaFoam to de-crud a new (used) motor I installed. Just went back to the DT50 this last oil change.

slivel

Oil discussions can get emotional so I'm not recommending, just giving my experience. Car: 914 with 3.4 liter twin plug six. Track only for 23 years. Used to run Mobil 1 15-50 until manufacturers started reducing the zinc/phosphorus levels. Then I started a 50-50 mix of Mobil 1 15w-50 and Mobil 1 20w-50 V-Twin motorcycle oil. Retired from racing and in the process of returning the car to street duty got a health check on the engine - compression check and leakdown plus had 20 years of oil analysis reports form Blackstone. Thought that I would have to overhaul the engine, but no. It still has great numbers so I am pleased with the performance of my oil.