Oil temp increase immediately after oil change?

[rs4vr]

Had my oil changed through Audi's maintenance plan.

For the last 3000 miles, I've run Pennzoil Ultra 5W40 and I believe the dealer uses Castrol Syntec LLX 5w40.

I noticed my oil temp went up by 15-20 degrees F for about 200 miles after the oil change.

The oil temp increase has slowly been creeping down to about a 10-15 degree increase over the last couple of hundred miles.

I've noticed the oil temp increase is most obvious when I drive moderately hard. It will go up to 235 sometimes and then only settles back down to 217-222, at idle.

My best guess is the Castrol 5w40 used by the dealer must be thicker than what I normally use, (Pennzoil Ultra 5W40) = increased heat.

Thoughts? Anything I should worry about?

 

[CATERHAM]

In theory thicker oil does run hotter and than retain heat longer than thinner oil but honestly in practice I haven't noticed it myself.

I'd look to another cause. Does you're car have an oil to air, oil cooler; I know you have a heat exchanger. Is it clear of any obstuctions, etc. Anyway, those oil temp's are nothing to worry about. At your next oil change go back to PU 5W-40 and see if the oil temp's drop; that would be the sure fire proof that it may indeed be the oil.

 

[cchase]

Where are you measuring oil temps?

 

[Astro14]

Correlation (things happening at the same time) is not causality (one of those things makes the other happen). There may be another explanation...out of curiosity, what else was done at this service? Have you been operating the car in exactly the same conditions (environment, route, traffic, etc.) as before?

Could be the Castrol - the PU 5W40 is a hair on the thinner side for a -40WT...but I would like to run through all the possibilities. When I had a turbo car with an oil temp gauge...I found that the oil temp was dependent on 1. Outside air temp and 2. how heavy my right foot happened to be...oil viscosity had little to do with it...

 

[chubbs1]

A thinner oil like PU 5w40 would probably decrease temps since there is faster heat exchange with thinner oils. So the issue is something else (most likely).

I agree with CATERHAM, use the PU again if possible. If the temps stay high on the second change and you go back to Castrol and they go down I would stick with the Castrol. Though, a few degrees like that shouldn't matter. There are so many variables as well. Just wait and see. No harm is being done.

 

[mechtech2]

Also, maybe it cleaned the sensor tip to read a bit different?
Thickness is a factor to be considered, but 2 40s should not be that different at operating temp.
And who knows what they really did put it?
Maybe a smaller oil filter was used?
A wire or connector brushed against and changed the resistance?

 

[LeakySeals]

Good question -what kind of filter did you use? What was in it before?

 

[Jeff_in_VABch]

Originally Posted By: mechtech2
Also, maybe it cleaned the sensor tip to read a bit different?
Thickness is a factor to be considered, but 2 40s should not be that different at operating temp.
And who knows what they really did put it?
Maybe a smaller oil filter was used?
A wire or connector brushed against and changed the resistance?


I doubt that the electric thermo couple in the oil pan would be affected no matter how inept the shop is.

However, like you say, who knows what they put in it for oil or filter. You could look at the filter.

The OP didnt mention how the oil pressure or coolant temp looks.

I would just go ahead and change it back to the original oil now. The temp isnt too high, but that much un-explained increase is a sign of trouble.

If the changed the O2 sensor or reflashed the PCM that could also affect the tuning or guage correction factors.

 

[JAG]

That's too much of a change to be due to the slightly different oils, in my opinion. Something else must be causing most of that change.

 

[Garak]

Originally Posted By: CATERHAM
In theory thicker oil does run hotter and than retain heat longer than thinner oil but honestly in practice I haven't noticed it myself.


I have in my old Audi, but that's comparing a 5w-30 or 10w-30 winter fill versus a 15w-40 summer fill. It's noticeable, but a swing like the OP noted (which is within the same grade) is a bit odd.