Why use thicker oil?

[FrankN4]

Doug

I have always run higher viscosity oils and have never had an engine problem. It may be as much because the oils I have used had a HTHS of 4.5, or so.

GM has engines that range from multi cam, multi valve, their simple V 6/8 engines, all the way to the "Bad Bubba" Corvette. At the same time, most XW-30, non HM oils, those recommended by GM, have a 100C cSt of an average 10.3 and an average HTHS of 3.0. Is that really sufficient to put 200,000 miles on a Corvette to a DOHC, 4 valve, 7000 RPM I4?

I can't tear an engine down. I use a simple mechanics stethoscope and a compression tester. I am used to arriving at the 200,000 mile mark(175,000-225,000)with no out of ordinary engine noise, compression within +/- specs, no oil consumption, and no oil seep/leak. I just can't get myself to believe that a 10.5 cSt and a 3.0 HTHS will deliver those kind of results.

 

[ARMY_Guy]

Originally Posted By: Zaedock
...If you plan on beating your Jeep, run a 40wt. As a fellow Jeeper, I typically run a SAE30 or 10/15W40 in my 2.5L & 4.0L Jeeps during the spring/summer/fall months.


Zaedock! Yeah Man, sounds goo; but I do want to use a thinner oil to get the goop out of tiny nooks and crannies, as I believe Dr. Hass alluded to in another post on another thread (Thin oil thread). Even as a "newbie, tech junkie, better than your average Joe though" Jeeper, I know one thing, thin flows better than not thin, and will undoubtedly help in cold starts, and other vehicle related tech things, You and a couple of others here have said the Wrangler engine loooooves a Xw40 oil, so thats the route I'll go, but I'd still like to run a super thin oil at startup, to offset the startup issues.

(Jeep Wave)
-A

 

[Doug Hillary]

Hi,
FrankN4 - Your experiences are consistent with my comments and those of others

The published viscosity of the lubricant is important and this is to some regard why we see the recommendations based on J300 (via the API) as alluded to on here - certain HTHS viscoity limits apply. Sadly they are a little confusing. The Euro makers have another more transparent approach with numbers

The API's HDEO "playing field" is somewhat similar to the ACEA protocols as they have been "honed" by direct involvement with the engine makers for well over two decades now. Their user Panels have done the job after a disastrous period some decade or two ago when the API was out of touch. They have been consistent with their requirement for a HTHS viscosity of 3.7cP

I would never have used a lubricant without DD's minimum HTHS viscosity (3.7cp) in my engines costing upwards of $50k each!

Not all lubricants are the same and even though some SAE30 lubricants (0W-30 & 5W-30 perhaps) may have a published HTHS vis around 3.5cP (the Porsche minimum) they have never passed the Porsche extended version of the ACEA's test protocol (as used for Porsche Approval) so none appear on their Approval List (not Cayenne V6 (VW)) and have not done so for nearly a decade

I know enough about Porsche engines to know that using a SAE30 (0W-30 etc) lubricant and driving the cars as they should be driven is a risk that should not be taken. Some people do and have had a trouble free engine life to date. M1 0W-40 does very well thanks and in some engines I even go a little further with Delvac 1 5W-40. Many Porsche engine builders use M1 0W-50 or 15W-50 as their "insurance". They know the engines!!

As you say sometimes a HTHS viscosity around 4cP may be a good insurance Policy in the "real world"

That said IMO it is wise to use only the viscosity of lubricant recommended and Approved by the engine's maker - and even then perhaps one Listed by them!

 

[Jason8691]

Originally Posted By: aquariuscsm
Here`s something I read in my friend`s new Mustang V6 owner`s manual:

V6 models-5W30
V8 models-5W20

Why would they recommend a 30 weight in their V6 and a 20 weight in their V8,BUT the Ford GT recommends a 50 weight (5W50)?

Are they trying to squeeze as much gas mileage out of their most popular car (Mustang GT) to boost it`s sales? I`d think a 20 weight would be recommended in their V6 over their monster V8 motor. Just a thought.

On a side note,that V6 Mustang runs like a beast! Sounds nice and throaty like a V8. I was VERY impressed! First time I`ve ever been in one. That car`s so comfortable it felt like I was sitting in a Lazy Boy recliner!


The V6 is not a Triton engine, the V8s are. Some claim tighter tolerances in the Tritons, hence the 5W20. The original Tritons used 5W30, so unless they changed the internals from the originals, a 5W30 is ok.

 

[crinkles]

Originally Posted By: FrankN4
Doug

I have always run higher viscosity oils and have never had an engine problem. It may be as much because the oils I have used had a HTHS of 4.5, or so.

GM has engines that range from multi cam, multi valve, their simple V 6/8 engines, all the way to the "Bad Bubba" Corvette. At the same time, most XW-30, non HM oils, those recommended by GM, have a 100C cSt of an average 10.3 and an average HTHS of 3.0. Is that really sufficient to put 200,000 miles on a Corvette to a DOHC, 4 valve, 7000 RPM I4?

I can't tear an engine down. I use a simple mechanics stethoscope and a compression tester. I am used to arriving at the 200,000 mile mark(175,000-225,000)with no out of ordinary engine noise, compression within +/- specs, no oil consumption, and no oil seep/leak. I just can't get myself to believe that a 10.5 cSt and a 3.0 HTHS will deliver those kind of results.


Frank, what is your OCI?

 

[OVERKILL]

Doug:

What are your thoughts on running TDT 5w40/Delvac 1 5w40 in a Ford 5.4L Triton?

 

[Doug Hillary]

Hi,
OVERK1LL - Firstly, I would use the upper end of Ford's viscoity recommendations for the engine if wanting to go with the most viscous lubricant "allowed". Synthetics in this range with Ford's endorsement are great lubricants. Ford have had nearly two decades of experience with low viscosity lubricants in their engines - I have not read any negative exposure to this in the form of Warranty claims and the like! Where heavier viscoities are specified in other World markets for the same engine - the same comments apply. The low viscosity lubricants work well where they are specified by the engine's maker!

Secondly I would consider M1 0W-40. M1 TDT 5W-40 or Delvac 1 5W-40 are quite viscous SAE40 lubricants and they would work well in this engine too but they may be outside Ford's allowable range of viscosities

If I owned such an engine, was living in a hot climate and "using" the uppermost performance from the engine, (and wanting to use a "suitable" SAE40 lubricant) I would use any of the lubricants noted above starting with M1 0W-40

 

[OVERKILL]

Thank you very much Doug. My wife and I are in the throes of attempting to acquire a 2002 Expedition with the 5.4L, and since I have a collection of the TDT 5w40 I was thinking I might run it.

I will definitely check the owners manual.

-Chris

 

[RadBOSS]

Originally Posted By: Steve S
If the 50w is really really hot it could be thinner than a 30 wt that is not very hot. I am not exactly where it is but there was a viscosity calculater where you plug in the temps and viscosity and get the viscosity at certain temps. I am just too dumb to get it all together . But everything changes with temps and rpms and the load on the engine. Engines are pretty flexible and stand up to our abuse otherwise they wouldn't give an average long life.


50 weight motor oil viscosity is right in range with 90 weight gear oil and about 50% more viscus at 210 deg F.

 

[FrankN4]

Originally Posted By: crinkles


Frank, what is your OCI?


3000 miles is my goal OCI. If I am going on a trip and the trip will have me home by 3500 miles, I will go to 3500. If the trip will not have me home by 3500, I will change before the trip whatever the mileage may be.

 

[BuickGN]

Originally Posted By: RadBOSS
Originally Posted By: Steve S
If the 50w is really really hot it could be thinner than a 30 wt that is not very hot. I am not exactly where it is but there was a viscosity calculater where you plug in the temps and viscosity and get the viscosity at certain temps. I am just too dumb to get it all together . But everything changes with temps and rpms and the load on the engine. Engines are pretty flexible and stand up to our abuse otherwise they wouldn't give an average long life.


50 weight motor oil viscosity is right in range with 90 weight gear oil and about 50% more viscus at 210 deg F.


Run the car hard on a hot summer day and see how thick the 50wt is at 280 degrees.

 

[AzFireGuy79]

My dad use to race unlimited hydroplanes in the 60's and 70's with allison and Rolls-Royce V-12's and he always talked about the heavy straight weights they use to use being still too thin at operating temps so they had to throw in some Hilton Hyperlube or Bardahl oil additive. Granted the tolerances of these engines is much greater than any automotive application and this was a long time ago, but being that I am very into running synthetic and low viscosity oils it was hard to wrap my head around.

 

[Shannow]

Originally Posted By: RadBOSS
50 weight motor oil viscosity is right in range with 90 weight gear oil


...and tomato juice

 

[3Toyotas]

So you all are suggesting a higher HTHC as well as a higher cSt @ 100 C?

SSO is 10.3 cst & 3.2 HTHC. So would this be better to run than a 0w20 that has a 9 cst & 2.8 HTHC for a 4 valve per cylinder all aluminum large v-8 towing in excess of 8k lbs?
I take it that real world situations are different as well?

Interesting thread here.

 

[Steve S]

Originally Posted By: RadBOSS
Originally Posted By: Steve S
If the 50w is really really hot it could be thinner than a 30 wt that is not very hot. I am not exactly where it is but there was a viscosity calculater where you plug in the temps and viscosity and get the viscosity at certain temps. I am just too dumb to get it all together . But everything changes with temps and rpms and the load on the engine. Engines are pretty flexible and stand up to our abuse otherwise they wouldn't give an average long life.


50 weight motor oil viscosity is right in range with 90 weight gear oil and about 50% more viscus at 210 deg F.
Really hot! Lets say 30wt at 175*f and 50wt at 275* I have drained oil from big block Chevies that have towed heavy heavy trailers by lead footed drivers in the middle 1970s that you would have to almost help the oil drain out. That oil got real hot.

 

[Steve S]

A fact that everyone should have to agree on and should be looked on as fact!!! the oil viscosity chosen should be thick enough to protect the engine for the most demanding operation encountered yet not overly thick as to cost power and mpgs.

 

[Steve S]

Originally Posted By: AzFireGuy79
My dad use to race unlimited hydroplanes in the 60's and 70's with allison and Rolls-Royce V-12's and he always talked about the heavy straight weights they use to use being still too thin at operating temps so they had to throw in some Hilton Hyperlube or Bardahl oil additive. Granted the tolerances of these engines is much greater than any automotive application and this was a long time ago, but being that I am very into running synthetic and low viscosity oils it was hard to wrap my head around.
I am sure those allison engines had tight control over the tolerances .The engines heat is really equal to the power it puts out .I would bet those engines would get the oil as hot as oil can get.The load on the engines must have been incredable

 

[Steve S]

Originally Posted By: 3Toyotas
So you all are suggesting a higher HTHC as well as a higher cSt @ 100 C?

SSO is 10.3 cst & 3.2 HTHC. So would this be better to run than a 0w20 that has a 9 cst & 2.8 HTHC for a 4 valve per cylinder all aluminum large v-8 towing in excess of 8k lbs?
I take it that real world situations are different as well?

Interesting thread here.
The question first is how hot does the oil get.Let me Drop Doc Haas name again I have read his papers and I read which is gospel truth is he runs 20 wt in his exotics because he knows that the driving he does does not heat up the oil enough to need more viscosity. One of my friends has a choice Ferrari 328 I have driven it enough to say I don't know what it would take to get the oil hot in that car. Driving uphill in top gear at top speed? The true oil temps and resulting oil pressure will tell what is needed.

 

[Doug Hillary]

Hi,
Steve S - It is not the bulk oil temperature that is so critical. It is the operating areas of the engine that depend on the lubricant to cool and lubricate. Some areas easily see around 175-200C outside of the "fire zone" and this is especially so with charged engines - the return to bulk oil temperatures tell some of the story

In these cases the minimum HTHS requirement is detemined by such things, as the component operating temperatues may be 100C or more abouve the bulk oil temperature. Wear can occur through the loss of the lubricant's film (viscosity) to a point that boundary lubrication is the only means left - at this point the destructive minor contaminants do their nasty tasks

 

[jldcol]

Complete non expert here but do not dino oil have a flash temp of 400-450, and syns about 50-100 degrees higher? What safety factor would want here? Most bearings get over 300 degrees with moderate loads, and pistons more heat 350+, so with dino only 50-100 degrees saftey factor. More power higher temps and even less safety factor.Eventually at some temp all oils get to same visc~, and a a higher temp get to zero viscosity essentially by turning to gas. This is for those that say my engine does not use any oil during say a OCI, little bits are being gassed off and sucked into cyclinder via PCV and burned up, all the time.