Guest bastaad525 Posted January 28, 2004 Share Posted January 28, 2004 This make sense to you guys? As some of you know I recently swapped out my Mobil 1 10w-30 for same brand 15w-50 (thinking the thicker oil would help with a minor leak that I have, which it did not). At about the same time, I notice that at night and in the morning, the car seems to be struggling a bit more when I start it cold. Once warmed up the idle is fine and is the same as it's been before the oil change, no noticeable difference, but when it's cold out and the motor is cold... the idle is a few hundred RPM lower than I'm used to seeing. The weathers been pretty chilly out too (relatively, I live in SoCal) dipping to like the 50's or even the 40's I think... does it make sense for those temps combined with the thicker oil to cause the car to struggle like this? Before, the car would idle at 700rpm when first started cold, and would raise up to 850-900 after driving only a few blocks, even when the temp gauge has barely started to move. Now it idles more around 500rpm when cold and only slowly increases only getting to 850 when the car is fully warmed up! So what do you guys think? Is the oil the culprit or should I start worrying? Quote Link to comment Share on other sites More sharing options...
jonzer12 Posted January 28, 2004 Share Posted January 28, 2004 When the temperature goes down you want a lighter oil, not a heavier one, lighter oils have better viscosity when cold. I would NOT run 15w oil in cold temps (I live in canada so cold to me is 0 to -35 celcius). If you are in subzero temps running a heavy oil like that is not helping your cold start protection. Your temps don't seem that cold to me but its not all that warm. I would save that oil for the summer and hit a 5w-30 or 10w-30. I would think that it could very well be the oil affecting your idle, IMHO. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 28, 2004 Share Posted January 28, 2004 yeah... again, I only tried the thicker oil to see if it would help with my leak, which it did not (actually seems to have made it worse, though I'm not sure if the increased leak does indeed have anything to do with the thicker oil), and also to see if it raised my oil pressure any at idle, as my gauge was reading a bit lower than the average recommendation here, which it also did not. Will probably switch back to 10w30 pretty soon then. Quote Link to comment Share on other sites More sharing options...
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