I need some help.

I have a 1300 xflow that I race with in the 750MC.

I keep getting two different answers of what oil I should run, some say 20w/50 mineral and some say 10w/40 semi synthetic.

What are the advantages of these and what would be best to run in my engine?

I asked the same question on an e type forum about my engine. The common answer was that if the crank has rope seals front or back I should use a good quality mineral oil, as synthetics, and semis, will weep past such seals.

[Edited on 9/6/11 by r1_pete]

Well I don't know the engine but generally:

The 20/50 will be more viscous at cold operating temps and will hold a higher viscosity at full operating temp. The 10-40 will be lower viscosity at both points. High viscosity oil sticks to stuff better, doesn't burn off as quickly when hot but introduces more losses. Lower viscosity will help starting and give you lower losses. But if your engine is not up to spec (lots of wear in the mains/big ends) the lower viscosity oil may cause oil pressure problems when hot in a race situation.

Stick on an oil temp and pressure gauge and try them both. Neither is going to give you engine death from one run unless you run a thinner oil too hot and lose all pressure.

Semis and synths should behave no differnt to dino oils and technically shouldn't be any different on the seals, if you have a leaky seal you have a leaky seal.
My engine is spec'd for 10w40, I used to run 0-50 synth as the hot oil, when the turbo had been on song for a while, dropped to ~7-8psi, the 50 grading took that back up to 17-20psi ish.

[Edited on 9/6/11 by coyoteboy]

depending on the mileage of the engine, roughly 75k would change from a 10w40 oil to a slightly thicker oil being a 15w40

the 20w50 is for the older engines / ones that burn alot of oil.

on anything older than a 96 ignore when people say to use a 5w30 oil as that wasnt even thought about untill the zetec's come into production.

for raceing etc, if you want to treat the engine you could pop in some 5w40's but not really something that is needed, just helps it flow quicker when warm because of how thin it gets


(thats my understanding of it from work with the advice i was given when selling it)

If you are racing you want oil preasure, If you cant get 10psi per 1000rpm on 10w40 use 20w50
A high pressure high capacity pump always helps.

Hi. A good 20/50 mineral oil such as Valvoline is ideal for the clearances in the oil pump and bearings of the crossflow but do fit an oil cooler or heat exchanger. I have seen sump temperatures of 130c when running a 750mc locost without a cooler and I wouldn't trust any mineral oil at that temperature. We have used semi synthetics in the past but the pump can struggle to maintain pressure when the oil thins out. We use fully synthetic in crossflow engines in ff1600 but the pumps are designed to suit the thinner oil. Maurice.

Valvoline 20W/50

My Haynes manual says 10W40, but I (and many others) use 20W50. I use Millers mineral oil.

If the engine's cold and the battery's a bit tired then 20W50 may make starting difficult, but I always keep my car on a maintenance charger when it's in the garage so there's always full-power starting when required.

Another vote for Valvoline race oil 20/50,I have used it for years when I was racing the Ducati singles then on the crossflow.
Denis.

Valvoline 20/50 for mine although it only gets used on the road