HTHS numbers

Patman · Mar 10, 2003

quote:
Originally posted by Dr. T: I believe the UOA's don't give the whole story. Traditionally, thicker oils have been used and are recommended when 1. racing (high temp/high punishment conditions) 2. long drain intervals (I can't see too many engines going 10k mi. intervals on convenience-store 5-30) 3. engine life is a priority (Euro. engines last longer than U.S.).

Where is the proof of this though? There are quite a few examples of good old American and Japanese engines going hundreds of thousands of miles, running 5w30 and 10w30 also. I don't hear many stories of European cars going 500,000 miles, other than Volvos. Terry Dyson has viewed literally thousands of UOAs over the years, and he knows I want maximum engine life out of my LT1. You know what he recommends to me? 10w30. I'm sure if he saw any evidence that 50wt oils make our engines last longer, he would've told me to use this thick oil in the summer. The fact that he didn't, speaks volumes, IMHO.

MolaKule · Mar 11, 2003

A 50 weight will cause bearing heating over and above that of say a 10W30 in any circumstances, because the more viscous oil layers have to sheared. The shearing force to shear those thicker layers is coming from engine Hp. Energy is simply being transfered from the engine to the shearing to the heating of the oil.

sprintman · Mar 11, 2003

Why do manufacturers spec 40/50 etc everywhere bar U.S?

buster · Mar 11, 2003

I just posted a link to the New Zealand site where a 4cly. Corolla calls for a 10w-30 or 5w-50 wt.oil from Mobil. Are you sure Molekule that a 50wt. is too heavy? [Smile]

Dr. T · Mar 11, 2003

Really? Most people I talk to speak about needing an engine rebuild at about 150k mi....that's U.S. v-8's on 5-30. Don't speak about those that have changed their oil every 3k though...that's not fair....you could probably get a million miles if you changed your oil every week...but, that's not practical. Personally, every car I've owned has consumed some quantity of 5-30. And, if it doesn't right away..it will. I think there's 2 issues...UOA's don't give the whole picture...hence, you can look at thousands of them. Most oils will lubricate. Period. No problems there. Will a 5-30 lubricate adequately? Sure...but, due to it's thin viscosity it will undergo a higher amount of breakdown and burnoff. It is more volatile. Some will go out the tailpipe...and most will coat the inside of your engine. Hence, the need for auto-rx. Bottom line is all oils will lubricate. The thinner ones, although providing immediate benefits of fuel economy will have a greater amount of volatility and breakdown. The Europeans having realized this, seem to be ensuring that these thin oils have some responsibility to the consumer and have labelled them as such, A1 or A3, etc.. Hey, if it ain't broke don't fix it....

MolaKule · Mar 11, 2003

Buster, Corolla's running 5W50, yes I still think that is too thick an oil. 10W30 sounds more reasonable. Dr. T, High viscosity oils for racing, I would agree, since racing involves quite a bit of fuel dilution of the oil. Sprintman, Why higher viscosity oils in the other countries? Customer expectations and historical precedent. I have two GM Burbs that have run 5W30's and 10W30's (synthetics) in the engines throughout their histories and each have over 260,000 miles without ring replacement, bearing replacement, or timing chain replacements. They have at times hauled 2/12 tons of wood at 70 mph for 600 miles at a time. All of their analyses have shown less than 2 digit wear values. If the 5W30's and the 10W30's were so bad, they shouldn't be running today.

TurboFrog · Apr 14, 2003

quote:
Originally posted by G-Man II:
quote:
Originally posted by Patman: This is what Mobil 1 emailed me just now about the HTHS numbers: >SAE 0W-20 (soon to be available): >2.6 >SAE 0W-30: >2.9 >SAE 0W-40: >2.9 >SAE 5W-30: >2.9 >SAE 10W-30: >2.9 >SAE 15W-50: >3.7 Not too impressive. Although I recall someone here posting higher numbers before. Perhaps their specs are too vague. Saying it's greater than 2.9 could mean it's 3.5 in reality. Although at the same time, why would they quote a lower number? Wierd.
Mobil continues to perplex me with they way the answer (or don't answer) tech questions. To say that 0w40 has an HT/HS of >2.9 is ridiculous since the oil carries an A3 rating, which means it has to have an HT/HS of >3.5.

All right, I gathered the Mobil 1 HTHS data on their new website. >SAE 0W-20: 2.61 @150 deg C >SAE 0W-30: 2.99 @150 deg C >SAE 0W-40: 3.6 @150 deg C >SAE 5W-30: 3.08 @150 deg C >SAE 10W-30: 3.17 @150 deg C >SAE 15W-50: 5.11 @150 deg C I got those number from this page, http://www.mobil.com/USA-English/Lubes/Product_Information/Automotive_Engine_Oils_Collection.asp I did some searches on HTHS number. Some people reported numbers @100 deg C, but Moil 1 tested @150 deg C. I think Mobil 1 HTHS are impressive, especially 15W-50. What do you guys think?

Patman · Apr 14, 2003

I personally don't think Mobil 1's HTHS numbers are all that impressive. Compare their numbers for 0w40 to Castrol SLX 0w30, they both have the same HTHS of 3.6 (yet Castrol is thinner) And comparing their HTHS to Redline there is a big difference. Redline 10w40 has a 4.7 HTHS, Mobil 1 0w40 is only 3.6, yet both oils are almost the same viscosity at 100c (M1 is 14.3cst, Redline is 14.6) I know it sounds like I'm knocking M1 a lot lately, but M1 is a great oil for an everyday driver, it's just not that impressive for extreme racing type useage. Schaeffer 10w30 blend has a 3.5 HTHS, compared to M1 10w30's 3.2. And Schaeffer's 5w30 full synthetic has an HTHS of 3.8! It's too bad they don't sell that oil in single quarts, and it's a shame they don't offer more full synthetic viscosities, such as a 5w40 or 0w40 so they could get a bigger market. [ April 15, 2003, 05:31 AM: Message edited by: Patman ]

buster · Apr 14, 2003

Mobil 1 does have some low HT/HS compared to other synthetics. For extreme racing, I think your right, Redline would be better.

5abi6r · Apr 14, 2003

I see that higher is better. But at what point is it overkill? My motor will be street driven but will often have the snot revved out of it at mosport and shannonville. What kind of oils, numbers should i be looking at? > the temperatures here in toronto are usually 20'celcius + during the months i drive the car (june-october)... and its stored in a heated garage every night. learning some interesting things,, thanxx ! [Happy]

Justin · Apr 15, 2003

What do the HTHS numbers look like on the three 15w-40 HD dino "fleet" oils, such as Delo 400, Delvac 1300, and Rotella-T?

Patman · Apr 15, 2003

quote:
Originally posted by Justin: What do the HTHS numbers look like on the three 15w-40 HD dino "fleet" oils, such as Delo 400, Delvac 1300, and Rotella-T?

Rotella T 15w40 has an HTHS of 3.9. Not sure of the others.

Justin · Apr 15, 2003

quote:
Originally posted by Patman:
quote:
Originally posted by Justin: What do the HTHS numbers look like on the three 15w-40 HD dino "fleet" oils, such as Delo 400, Delvac 1300, and Rotella-T?
Rotella T 15w40 has an HTHS of 3.9. Not sure of the others.

Thanks for the reply Patman. Justin. [ April 15, 2003, 03:15 PM: Message edited by: Justin ]

buster · Apr 15, 2003

quote:
I see that higher is better. But at what point is it overkill

Depends on the engine but Mobil 1 seems to be more then enough. I have yet to see another oil with higher HT/HS out perform it. [Smile]

boxcartommie22 · Apr 15, 2003

delvac 1 5w40 is 4.1

buster · Apr 15, 2003

Yes, D1 is 4.1 and M1 15w-50 is 5.1. The way i look at it now, is M1 is fine for 99% of all cars made and up to around 10k miles of oil life. (generally speaking). I think Amsoil can hang in there a little longer and is probably better at longer drains. Redline for high hp cars and racing. [Big Grin]

[ April 15, 2003, 09:30 PM: Message edited by: buster ]

MolaKule · Apr 15, 2003

Boxcar, In answer to your original question, the HTHS number is a quality number given to an oil's resistance to shearing and at high temperatures. An oil will shear its layers under high mechanical shear which is similar to pushing the top of a column or cylinder of pudding or jello. The higher the HTHS number, the more resistant it is to shear thinning. In my view, any number greater than 2.8 is probably a good indication of that oil's resistance to thinning by shear forces.

HTHS numbers

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