Triumph Repair: Spitfire 1500 oil pressures, triumph club, regulator valve

Question
Hi,
   i have a 76 Spit and can't get a straight answer on what the oil pressure should be,previous owners put a pressure gauge on that reads 65lbs when cold and goes down to about 15lbs at idle after driving around in the summer heat,the car is fine running around town and stays pretty cool even stuck at the many red lights in Winnipeg,problem is after about an hour at highway speeds 55-60mph the pressure slowly drops to around 35lbs. the engine is not new so maybe it's ok but i get so many varying answers from the guys in the local Triumph club i need an independant opinion.Thanks,Barry

Answer
Hi Barry,
Your pressures hot are a little low but there are several factors involved. First is what weight oil are you using? You should have at least 20w40 in the summer and 10w30 or 10w40 in the winter. The condition of the pressure regulator valve can also play a part even at idle if it does not seat well and have a good spring.
Most Spitfires I seen in the dealership I worked in were form 20 to 35 PSI at idle (hot oil) and from 45 to 65 PSI on the road at 2000 RPM-up.
If it were mine I would make sure the oil was correct and replace the pressure regulator valve and spring and then you will have a better picture of the condition of the bearings.
Howard