Engine smoother after oil change

Joined
Jan 23, 2014
Messages
542
Location
Australia
Hi guys,

I know for the most part there must be a placebo effect, but recently I changed the oil in my 6G75 Mitsubishi Diamante and I genuinely believe it got smoother.

I went from Castrol Edge 5W40 with 6,500 miles on it to Valvoline SynPower 5W40.
The engine is in good condition with no sludge, not even varnish (internals are raw aluminum color).

I have driven the car a few times now and just think to myself it is running smoothly, then remember that I did an oil change.

Is this possible?
The only thing I am thinking is whether different oils stick on the rotating assembly in different amounts which changes the balance and hence NVH?
 
Joined
May 25, 2005
Messages
14,930
Location
ROCHESTER, NY
In my experience most oils are about the same. However now & again I use an oil(popular name brand) that does in fact make my engine seem less refined and slightly more audible for the whole OCI. NO, this is not in my head as it has been discussed at length here at BITOG. This is why I try to stay with the brands that make me happy. I call'em my go-to" oils and I do have my favorites.

And I'm not a "Thick vs Thin" oil guy. I've used 0W20 that kept my engine(s) as quiet & smooth as I expect them to be. And I've used 5W30s that made my engines more audible and less refined sounding & feeling. Noticeably so! :eek:
 
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Joined
Jan 22, 2011
Messages
7,859
I think it's the same reason its best to have clean oil before getting emission tested. Contaiminants in the dirty oil and crankcase vapors passing thru the PCV system to be reburned then sensed by O2 sensors and the fuel mix is adjusted accordingly. I have experienced the same with my engines and has nothing to do with the brand or weight of the oil used.
 
Joined
Jul 3, 2005
Messages
37,746
Location
NY
The only things that come to mind when I read about engines running smoother, and quieter after an oil change is:
1. The oil drained in the sump was shot, perhaps thinned down from excess fuel or the oil was in use too long.
2. And/or they bumped up a grade or two.
3. And/or the filter wasn't working properly.
4. And/or there is a mechanical condition the fresh oil is fixing. Worn rings? Or just a better ring seal?

It's early that's all I can think of now.
 
Joined
Aug 26, 2009
Messages
313
Location
UK
even with the same viscocity rating, there is a variation in the actual oil technical specs so this could a partially the cause.

Also you change the oil yourself as opposed to a garage or a dealer. I have also found the engine smoother since I startind to the the oil change myself!
 
Joined
Dec 28, 2014
Messages
2,350
I occasionally get this “effect”. Hasn’t been in a pretty long while until recently I tried Mobil1 EP 0W20. Engine seems “smoother”, acceleration seems smoother. I don’t get it. I know that it can’t be the oil, or perhaps it can, but it is frowned upon to even suggest. 🤣🤣 But yeah something felt “different” to me.

And not for nothing, I listen to engines all. I work in this trade. My ears, I guess you could say are trained. Trained to hear things that quite frankly, I don’t want to hear. Like, when I’m on vacation in Barbados and the taxi driver picks me up and I tell him he needs a water pump and left wheel bearing. And he says, yeah you’re right, how did you know that? And I tell him it’s a magical gift, and for $20 bucks I can also tell you what you’ll be eating for supper tonight. Never mind that I could smell the coolant, see it dripping, and hear that wheel bearing getting louder every time he turned the car to the right. Lol. Magic. It’s a “gift”.
 
Joined
Nov 20, 2006
Messages
29,169
Location
MA, Mittelfranken.de
Next time you change the oil give it to your wife to drive without saying anything like "tell me if it feels different to you" just a blind test. If she says nothing your mind is playing games which is the usual cause for this common phenomenon.
 
Joined
Apr 18, 2013
Messages
1,228
Location
Kevil,Ky
On my 07 Ram hemi which has always had Castrol GTX high mileage for the last 10-12 years, I ran it on Valvoline full synthetic for 2 changes. It ran smoother and quieter than ever. I went back to the same old Castrol though since it had been on that oil since birth. At 220K miles with no issues, why gamble? My wife's Mazda had Mobil 1 in it and at 32K I switched it to Havoline synthetic. I ran much quieter with the Havoline.
 
Joined
Sep 17, 2012
Messages
2,311
Location
A Barrier Island
Never experienced that oil change/smoother correlation but my vehicles almost always respond positively to getting a nice wash and wax. I know correlation is not causation but still undeniable.
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FZ1

Joined
Feb 7, 2008
Messages
5,902
Location
Texas
Hi guys,

I know for the most part there must be a placebo effect, but recently I changed the oil in my 6G75 Mitsubishi Diamante and I genuinely believe it got smoother.

I went from Castrol Edge 5W40 with 6,500 miles on it to Valvoline SynPower 5W40.
The engine is in good condition with no sludge, not even varnish (internals are raw aluminum color).

I have driven the car a few times now and just think to myself it is running smoothly, then remember that I did an oil change.

Is this possible?
The only thing I am thinking is whether different oils stick on the rotating assembly in different amounts which changes the balance and hence NVH?
If you think it's smoother......... then it's smoother. You know your ride better than anyone else. Could be a difference in oil viscosity at purchase for 2 different brands, or at the time of the oil change, as oil usually thins over the oci. So yeah, it's possible/probable.
 
Joined
Jul 30, 2003
Messages
2,348
Location
GA
I've noticed this. One particular vehicle is outright archaic sounding on one particular oil yet quiet on a particular other brand. I'm thinking some engines just aren't as transparent noise-wise as others. I honestly don't understand how an oil can make so much difference, and the noisy oil I've experienced has a very good reputation, and was thick for its grade.
 

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
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PNW

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