Viscosity Choice based on Oil temp

[KL31]

I've always noticed my car runs nicer the hotter the weather is and the longer I've been driving. I installed an oil temp sensor with digital gauge yesterday. The oil temp takes far longer to equal the water temp but when it does, it exceeds water temp. Highest I had was about 83C after 10kms (20 mins) of driving in mild climate (25C outside).

My work commute is around 20kms in 20-35 minutes depending on time of day (drive home always takes longer because soccer mums).

My car specs 30 weight but I'm thinking about heading towards a thin 30 weight. Thinnest I've run was formula shell 5W30 several years ago (car ran fine). That was around 10cSt at 100C.

If my oil cooler (stock) is doing a good enough job to keep oil temps below 100C in summer weather, I'd wonder if a 20 weight would be fine in winter? Most people are against it as it's specced for 30 weight only. However, I have seen one UOA with the same engine here which compared a bunch of 30 weights and also a 20 weight. The 20 weight had slightly higher wear metals but it was honestly still quite low.

Now my actual question is along the lines of: Is a 20 weight at low temps actually thicker than a 30 weight at high temps. Is a 20 weight at 80C still thicker than a 30 weight at 100C? Does that mean no harm would be done so long as the temps remain low? Or is the "film strength" of the 30 weight still stronger even when it is at far higher temps than the 20 weight?

A viscosity calculator I downloaded (someone here made it I think) says that the 20 weight oil I've entered would be 12cSt @ 85C. The 30 weight I'd use would be 11.8 @ 100C. Basically the same depending on oil temp.

 

[zeng]

Your car runs nicer when temperatures of it's moving parts (not oil per se) are 'hot' and normal.
To get the engine moving parts 'hot' and normal, within a shorter duration after a start, the following helps namely:
a)a hotter ambient;
b)a shorter shutdown prior to a start;
c)after a longer duration of driving, harder driving preferred;
d)run at high rpm at all times at say, 3000 to 5000 rpm; and among others,
e)a thicker oil in thicker 30 or a thinner 40 etc.

No, in your context of 'making' the car runs 'nicer' shortly after startup, don't go for thinner 30 or a 20.
JMHO.

 

[Shannow]

Given that your car is stock, with stock cooler, and the OEM specs a 5W30, then they've chosen that viscosity for the conditions that the engine produces.

I'm somewhat interested in why you are equating a 20 at 80(ish) versus the specced grade at 100(ish), and hope that you aren't taking University 101 as gospel...if your engine only gets to mid 80s on the specced oil, then that's as per design.

Spent part of my growing up in South Oz, second intake into Thomas Moore College near Parafield.

 

[FCD]

Try a synthetic 0w30 , they tend to be on the thin side

 

[SR5]

I have a 15km commute and I have been playing with viscosity for the same reason, getting it to warm up quicker.

Car specs a 15W-40 or 10W-30 in A3/B3 or A3/B4.

I tried a full syn, high VI 5W-40 - no joy. Then a full mineral, low VI 15W-40 - a bit better. Now I'm using a semi-syn 10W-30 and it's the best so far. All Euro A3 oils. I don't have a temp gauge, just going by warm up tick.

I have no answers, but I'm thinking about trying a full syn 10W-30 A5/B5 oil, which is a thinner oil.

 

[KL31]

Originally Posted By: Shannow
Given that your car is stock, with stock cooler, and the OEM specs a 5W30, then they've chosen that viscosity for the conditions that the engine produces.

I'm somewhat interested in why you are equating a 20 at 80(ish) versus the specced grade at 100(ish), and hope that you aren't taking University 101 as gospel...if your engine only gets to mid 80s on the specced oil, then that's as per design.

Spent part of my growing up in South Oz, second intake into Thomas Moore College near Parafield.



I'm actually only a few kms east from Parafield! I'm just curious and have next to no idea about oil apart from the very basics. I'm going to monitor the oil temps on the way to work during some cold weather this week. When summer hits I will compare data. I am almost positive that summer will produce oil temps near 100. Winter, not so sure.

Cooling system is stock but I have removed the AC system completely including condenser. So the radiator is getting better cooling. The cooling system is somewhat beefy for this car also. It can take up to 10 kms for thermostat to open at 80. If I go down a long hill and the ECU cuts fuel and spark, it drops around 10 degrees below thermostat opening (which is 82). So during the winter, I wonder what oil temps will be after 20kms.

Car is also over 20 years old and were first produced in 92, which means they were developed earlier than that. Manual only mentions API SH... This is why I wonder if a good quality 20 weight would have no issues. I know that the obvious answer is "just use the specced oil" but this forum would be much more boring if everyone followed the rule books 100%

 

[Shannow]

Cool, and good info...we were in Dexter Drive, Salisbury East...the suburb named after the cricketers (Dad was related to Max Walker by Marriage, which was the topic of conversation every time we went past Walker Drive).

If you want quicker warmup, hold a lower gear while traversing the suburbs.

For the same load (road speed), there's a LOT more heat put into the oil at higher RPMs...

Holding "2" in my Caprice for the first couple of km gets the thermostat open about the same time as I hit the edge of town, or the highway on the way home.

 

[bbhero]

This great advice from "the Professor" on this. I have done this as well and it does work very well in the winter time to help my car heat up faster. I was hoping he would help out with this question by the OP here. One of the best on here.

 

[KL31]

Dexter drive wow, that's about a 5 minute walk to my house as I'm also in Salisbury East

I'll give the lower gear faster warm up procedure a try tomorrow morning. Although my gearbox does have stupidly short gearing already. 80kmph down main north road is 2500rpm in 5th.

 

[SR5]

Yes, Professor Shannow.

 

[FCD]

My daily commute is about 14 Km each way , it takes around 15 Minutes , 90% motorway driving and driving at around 120 Km/h all the time the little 1.1 Petrol engine in my Peugeot 106 does warm up pretty quick, it's a very rev happy engine i usually floor it when i'm merging onto the motorway to get in the left lane asap, although until i get on the motorway from my house it takes about 5 minutes so the engine isn't stone cold... also being an aluminium block i believe it doesn't take much to warm it up

 

[Shannow]

Originally Posted By: KL31
Dexter drive wow, that's about a 5 minute walk to my house as I'm also in Salisbury East

I'll give the lower gear faster warm up procedure a try tomorrow morning. Although my gearbox does have stupidly short gearing already. 80kmph down main north road is 2500rpm in 5th.


Please do give us feedback on any changes trying it that way.

We were at 21 Dexter...35 years ago...wallpaper down the hall was the AZTEC 2012 calendar thing.

Had an above ground pool where that queenslander building is, an obviously no tiki room.

 

[demarpaint]

What is the rpm range you try to hold it at for the faster warm up?

 

[Drosselmier]

why not try a 90*C thermostat? It would warm up a little quicker. Quote- " Heat is Your Friend "

 

[69GTX]

Originally Posted By: FordCapriDriver
Try a synthetic 0w30 , they tend to be on the thin side


Just the opposite from my experiences. They tend to be thicker at operating temp than your typical 5w-30. For example look at Castrol 0w-30 which has often been called a weak 40 grade. And in the Mobil 1 line they offer M1 0W-30 ESP which has an operating visc of 12.0 compared to the 11.1 of regular M1 5w-30. It really comes down to the specific oil. Unless the 0w-30 is specifically designed to be thin for fuel economy (like Mobil 1 AFE 0w-30 which is thin) I would expect it to have a higher viscosity than a standard 5w-30.

 

[just_me]

One of the big advantages of synthetic is that they flow better cold, and retain viscosity hot. So yes, its "thinner" when its freezing out, but at operating temp it should be more viscosity stable.

In the end, i think you are dealing with minutia here... just use a good 5w30 and move on

 

[KL31]

First test to work. Outside temp was around 10C and will be the same for next 3 days. Will have to do some thorough tests of the sensor itself at some point. But the results are:

Max oil temp 76 degrees. Was going up and down from 70 onwards.

The lower gear procedure worked well at getting water temp up a little faster. Oil was at 64 by main north road and grand junction intersection. Will drive using 5th gear tomorrow and note temp in same spot. There's not much traffic at 6am so test method will be the same. Not sure I like holding 4th at 80kmph 3000rpm. Can't be the best for fuel economy.

Will post drive home results later today.

 

[zeng]

Originally Posted By: KL31
Max oil temp 76 degrees. Was going up and down from 70 onwards.


Over-cooling ??

 

[Shannow]

Originally Posted By: just_me
One of the big advantages of synthetic is that they flow better cold, and retain viscosity hot. So yes, its "thinner" when its freezing out, but at operating temp it should be more viscosity stable.

In the end, i think you are dealing with minutia here... just use a good 5w30 and move on


Why since you came back do you insist on changing the thread topic lines to your P.O.V. ???

 

[KL31]

Drive home took slightly longer than drive to work and outside temp was around 17C.

Oil temp reached 85 max this afternoon. I was definitely driving a little less relaxed as the traffic was worse compared to morning. I don't experience any real grid lock or slow traffic on my route. It's generally smooth sailing with the occasional red light here and there (I never go through the city).

Will drive using 5th tomorrow morning to compare warm up.