[svxistentialist]

Originally Posted by JONES OFF ROAD

Gday All,
Now that I dont have an overheating engine, I am getting the buggy ready for racing again.
The next race will be 700km long, non-stop (except refuel) with an average speed of 120km/h, and my engine running over 6000rpm for 90% of the race.
What oil viscosity do people suggest?
Obviously I will use full synthetic, but should I use a straight or variable grade, if so, what grade?
Ambient temp should be about 25 deg celsius, engine temp should be around 85 deg c, and engine is in stock form.
I am a bit worried the engine might not stay together under these conditions, and would like to gear-up for less rpm, but that will sacrifice acceleration, which I am already 40-50 whp down on the nissans and toyota engines....so I guess I will just hope for the best!!!
Thanks, Steve

Steve

The best of luck in the race. I hope for two things really, that the cooling gremlin is in fact licked and your engine runs the distance to prove this, plus naturally that your engine holds together on the mechanical level. Make sure your tensioners are good and you have a decent cam belt. Running those high revs will seek out any weaknesses.

Subaru Owners' Manual recommends API grades of SF and SG. These are old grades and I think only SG is now in use, modern synthetics have gone far beyond these capabilities.

The manual also cautions against using 5W-30 for sustained high speed driving, so this flags a potential problem for you. 30 is not good enough for the heat

Steve if I was undertaking your race I would use Mobil 1 15W-50. It is expensive and it might seem a bit like overkill, but you will need the viscosity that the higher number will give you.

As I said, best of luck mate.

Joe