Impreza + Valvoline Maxlife = rough idle

[pickler]

So i was running Castrol Edge Ti 5w30 in my impreza 2.5i from october. i was generally happy except that my engine burnt about a quart with only 3k miles. So i switched to maxlife synthetic blend 5w30. Maxlife was my choice because it was the only high mileage oil with a respectable -45'c pour point. After the switch there is no more burning smell or burning oil but the car idles rough. ie. im at a redlight and the car is vibrating slightly, but if i drop it into neutral the vibration is gone!? There is slightly more engine noise as well during low rpm acceleration. Any thoughts? it is the oil right?

Car is 2009 impreza 2.5i with 45k miles

 

[Hyde244]

It sounds like you have seen some "severe" service if you are burning a quart every 3k miles.

Naturally you could try a full synthetic 5w30 to see if there is a difference. However I have the feeling this rough idling lies outside of your oil selection - it would be worth having a second look over your engine and systems to make sure everything is in good order. There are any number of other factors that will cause rough idling outside of oil type.

 

[randomhero439]

Sounds like a transmission, motor mount or sludge issue.

DOUBT it is an oil brand issue.

 

[garlicbreadman]

i doubt the oil is causing your engine to vibrate more. i can sometimes feel the vibration on my car and other days i cant..


and of course in an auto when you put it from D to N, vibration will almost be non existent..

 

[vwGLI]

I would say it's totally normal! Every car i drove did shake a bit in gear.

 

[pickler]

thanks for the response. i have been suspecting the transmission however the car used to be less turbulent overall before the change. cold starts where not so great but they were rather quiet. now it starts faster with valvoline but it makes a bit of rumbling noise. i had the maf sensor and transmission checked recently. the maf sensor was a bit off but it was fixed. if this indeed has nothing to do with the oil then im happy, because so far not a drop of oil has been burnt.

 

[salv]

I have noticed when I change to a different oil, my engine runs rougher until the new oil has been in the motor for a few hundred miles. I suspect that it is the product of one additive package working to replace the additive layer put down by the previous fill, and once this happens things smooth out.
On another vehicle that I owned, I knew that I had a torque converter issue. When I used a thicker oil, it slowed the crank enough to allow the torque converter to "catch up" and rotate in sync. When I used thinner oils, idle was higher and erratic, and the torque converter strugled to go into lockup as the crank would rotate past the torque converter.

 

[PZR2874]

Can you get ahold of Rotella T6 up there?

 

[bigjl]

I noticed that the Clio is slower to turn over from a cold start since going over to Maxlife Diesel 10w40, I think I ran 10w40 once a few years ago and there was no difference, engine runs fine otherwise.

Sounds more like your tickover is dropping slightly for some reason.

Have had similar in autos over the years.

Never in my auto Legacy.

I suppose it is always possible the oil is slightly less viscous than the previous oil and this very slight amount of additional drag has reduced tickover very slightly.

I have always found Subarus to use a little oil, especially if driven hard or at prolonged high revs and speed.

My Legacy did so and so did my WRX, they were both bought new.

Driving around locally I never noticed much oil use but I would need to top up a bit if I drive it to Scotland or when I drove it to Disneyland Paris.

VW vehicles also tend to use a little oil.

 

[GSCJR]

GTA recent ambient temperature = -17c...that will do it...it's fine.