sluggish 400 bhp STi after oil change
 

Hi guys, recently had a RCM oil catch can fitted with a return to sump connection on my forged hawkeye STi. The mechanic (a very reputable Subaru specialist) had to drain all the existing oil (miller CFS 10w50) and fill up with Ravenol 10w60. I did think this was too thick but he uses it in his track car and swears by it. He said because of the mods and the power output of the car, 400 bhp, its would be the best grade of oil.


Now after the oil change the car feels very sluggish and no way as punchy and quick as it used to be, almost as if the turbo is struggling to spool up.


Could this be directly related the thicker viscosity of the oil?


I did add a fuel system cleaner to the fuel too but have used loads in the past and they have never had negative effects on power


Any help appreciated

I would never put fuel cleaner in a Scooby mate,,, no need if your running her on v power.....

Always use Vpower and have always used a fuel cleaner every other oil change with no problems.


Am thinking the thicker oil must be the culprit, just need this confirming if anyone can help?

The oil is very unlikely to be the cause of your problem. Have you checked all hoses for an air leak? You may have a fuel blockage possibly caused by the cleaner. It's all guesswork you need to take the car back to your mechanic and let him diagnose the problem.

Just read the 10w60 can cause a lot of drag in the engine and loose bhp, Surely not to the extent of the power loss i'm experiencing. Will check hoses tomorrow, every thing looked ok when I had a nosy under the bonnet this afternoon.

No way it is the oil. The viscocity is only 10 different at 100 degrees

Has to be something else

Here is the fuel system cleaner I used as recommended:


http://www.opieoils.co.uk/showproduc...em-cleaner-vs1&


Have nearly used the tank of v power with this added to it so will refill with fresh vpower and see if that helps.


Only other this I can think of is if the addition of the RCM oil catch can has affected the breather system in some way?

If you have access to plug it in and run LearningView, would show if timing or mixture is being altered significantly. Could be caused by the cleaner being used

Could also reset ecu

Don't think the oil will be the issue here

My tuner did pug in his laptop to view mixture and said it was spot on. He didn't make any changes what so ever. I added the fuel cleaner when I got home and that's when I started playing up. Must be due to the cleaner then.


Hopefully with a fresh tank of juice it will sort the problem. When you say it could reset the ECU, do you mean I lose the map? I hope not as there is a lot of mods on the car all tailored to the map!

i use 10/60 millers in are rally car and it is sluggish when cold and shouldn't be used in a road car in my opinion.
10/50 miller would be a better choice unless you track the car alot.
i would swop it to be honest.
the 10 is the thickness but the 60 is the opituim temp range of the oil and if you dont stay in the range it can cause sluggish boost

Resetting the ECU won't lose your custom map. (Not to be confused with reflashing).

Fresh tank of fuel and it should gradually come back.

And loads of scoobs are run on 10w60, nobody would be able to feel the difference between a car running on that rather than 10w50.

Just a thought, when did you last change the fuel filter?

Fresh tank of v power and the problem is solved. Must have been the fuel cleaner confusing the ecu a bit. Back to pulling like a train and popping and banging like she used to, just how I like her, happy days :)