Why is fresh oil - significant difference

[goixiz]

I have a Saab 92x = subaru wrx wagon (EJ20) 2005
Ive been using GC for the last 8 oil changes
OCI ranges from 4000-5000 miles depending if im tuning the car or how hard i drive it.

After an oil change (today) last oil lasted 4300 miles. I would assume Im not using the full capability of the oil. Im starting to think i may want to go back to a non synthetic because - main reason = After an oil change my car runs so much smoother and i certainly can feel the acceleration and definitely pulls harder. Maybe frequent oil changes with a less $$$$ oil may be preferred for me.

Main Question - Why after changing the oil i feel such a significant (GOOD WAY) difference. IS there anything i can do to keep the Positive feel last longer and not degrade within 3-4k miles

 

[PF52]

A SIGNIFICANT difference? Wow, your old oil must've been pretty [censored].

 

[MGregoir]

Use a 5W-40 oil rated ACEA A3 oil, it won't shear down as much. A good oil for this would be Q HorsePower 5W-40 which is rebottled Shell Helix Ultra 5W-40.

The only thing I can think of is viscosity decrease or the turbo nuking it, which should not be that bad with GC.

 

[Bryanccfshr]

What I am thinking is your friction reduction additives are not as effective toward the end of your OCI(as well as potential oxidative thickening from turbo heat). I don't think increasing viscosity is going to change your perception. Try an oil that meets the manufacturer specifications and has a good friction reducing package. If energy conserving oil (such as mobil 1 5w30 PP etc..)is allowed by your maker, try some, these oils actually have great additions of friction reducers that may give you the results you want.

 

[goixiz]

i have a lot of GC left (30+ qts) bought when the sale and scared of no more GCs left in 2006.

Maybe add 1/2 bottle of SLOB in the middle of OCI
(also have a lot of SLOB)

 

[Bryanccfshr]

That is a nice stash of GC. I am suggesting that you try mobil 1 5w30 or PP 5w30 for an OCI and see if you like it better as a driver. After that you can 2 things. Keep the GC and use it or Sell the GC for Fair value(there are plenty of buyers I am sure) and use the other oil if you like it better. Doesn't mean the GC isn't a great oil, it may simply not be the best fit for your application or engine. It's worth a try IMHO.
I don't believe the slob would be as good as a fully formulated low friction engine oil.

 

[d00df00d]

MGregoir, GC for a while was, for most purposes, the most shear stable oil known to exist. It may still be. It'd certainly hold up better than almost any 5w-40, given that 5w-40s always need VIIs of some kind.

Also, keep in mind that GC was derived from the same chemistry and formulation as the factory oil in the B5 Audi S4. That car had two turbos with barely-adequate intercoolers in an extremely cramped engine bay -- and it all had to be comfortable spending long periods of time at redline under full throttle. If that oil can stand up to those stresses, it'll probably work just fine in any (remotely stock) modern Subie engine, turbos or no. Subie's boxer-4s are smaller and far more generously accommodated in the engine bay.


To the OP: Before you act based on your impressions, make sure they're not just the butt dyno talking. Few things make a car feel better than maintenance you feel good about. Heck, even if there is a difference, in the grand scheme of things it's very small if not negligible.

Either way, a good synthetic will always work better, longer. If GC lasts 4,000 - 5,000 miles before you start to feel a slight performance loss, a non-synthetic might not even last 3,000. Consider that, as well as the difference in protection under hard driving, when you make your choice.

If you're really unhappy with GC, you might want to consider stepping up instead of down: Motul 300V and RLI BioSyn would probably be much more consistent over the OCI (and are definitely killer lubes to begin with). 300V could take you out to 7,000-8,000 miles if your engine is running very well; BioSyn will go way longer (and costs a lot less to boot).

 

[goixiz]

Trust me i want GC to work otherwise i would not have got my stash.
I know its butt dyno and not something more. But everytime i change oil i ask the same Q (why it feels so good. Maybe the filter ? but i use Purolator Pure One. I do have a few M1 filters on the shelf.

Or maybe i have to get the overpriced OEM. OR maybe ill just bite it and get some WIX

 

[02zx9r]

Originally Posted By: goixiz
Trust me i want GC to work otherwise i would not have got my stash.
I know its butt dyno and not something more. But everytime i change oil i ask the same Q (why it feels so good. Maybe the filter ? but i use Purolator Pure One. I do have a few M1 filters on the shelf.

Or maybe i have to get the overpriced OEM. OR maybe ill just bite it and get some WIX


Believe it was Saturn fan who stated " I know I have an oil problem, but I dont want any help!"

 

[Lazy JW]

Originally Posted By: goixiz
... Why after changing the oil i feel such a significant (GOOD WAY) difference. IS there anything i can do to keep the Positive feel last longer and not degrade within 3-4k miles


Placebo?

 

[steve20]

We must have the same butt dyno- but mine also kicks in after I spend the day washing, clay bar, and Zainoing...so who really knows?

 

[d00df00d]

Originally Posted By: goixiz
Maybe the filter ? but i use Purolator Pure One. I do have a few M1 filters on the shelf.

Or maybe i have to get the overpriced OEM. OR maybe ill just bite it and get some WIX

I doubt one filter would be so much more restrictive than another that the difference in engine response would be noticeable. At most, there'd be a difference in cold start lubrication on very cold days.

Of course, if you switched from a Purolator Pure One to an El Cheapo Cheesecloth-In-A-Can filter or something, that might be a different story...

 

[dickwells]

Hypersensitivity

 

[d00df00d]

Originally Posted By: steve20
We must have the same butt dyno- but mine also kicks in after I spend the day washing, clay bar, and Zainoing...so who really knows?

As much as I scoff at the idea of any equivalence between looks and function, I get the same thing sometimes.

 

[nascarnation]

Originally Posted By: dickwells
Hypersensitivity


or "In God we trust, all others bring data"

Given the reasonable cost and wide availability of performance measuring tools today, it's not difficult to quantify this stuff.

or "Without data you are just another manager with an opinion"

 

[goixiz]

im able to log every parameter the ECU sees
let me know what you want me to log as the oil is less than 200 miles now and i can log again at 1000k (and increment of 500) and see if it changes.

i would assume
specific rpm on a flat road with temp, speed etc,....

but the most significant i feel ( i know my car fairly well)
1. if i downshift 3-2 to slowdown for anything it decelerates smoother.
2. ive got a fairly stiff driveline and bushings, when i accelerate (holding on shifter) i can tell its smoother.
3. Accelerating on an on ramp its definitely a difference there.

i am sure of the feeling is not a placebo - so i can rest but its not

 

[oilyriser]

Track fuel flow at idle speed over 10 days, in park, lights off, foot off the brake, vent fan off, and power steering not under any stress. Make sure each reading is made at the same coolant temperature eg. just before the rad fan comes on, but not during since this burns extra fuel. Measure this data before and after an oil change, and see if there is a step in the data.

Idle fuel consumption is the most sensitive way to detect changes in oil friction, since internal losses are nearly 100% of engine load.

 

[mxhdroom]

I just changed my dino for synthetic for the first time in the Sentra today, and I can't believe the difference. Quieter, smoother, seems to rev easier. Placebo or not, it works for me!

G.

 

[goixiz]

Originally Posted By: mxhdroom
I just changed my dino for synthetic for the first time in the Sentra today, and I can't believe the difference. Quieter, smoother, seems to rev easier. Placebo or not, it works for me!

G.


im not alone

 

[goixiz]

Im not sure i have fuel flow
what i will log (after 5 min of idling) for 3 minutes
RPM
injector duty % and Volts
AFR
Radiator fan (on or off)
water temp
MAF (g/s)
engine load

will do it as a baseline and then 500 and 1000 and 2000 and 3000