Discussion on oil weight

[reluctantartist]

I don't want this thread to get off topic and become a regular argument over which brand is best. I have been doing some reading on the pelican parts forum and all of the porsche people say to use 20w50 in the summer or 40w. I did find a post on HTHS on brad penn oil :
SAE Grade                                HTHS (mPa-s)

0W-30                                      3.38

10W-30                                     3.54

10w40                                       4.23

20W-50                                     6.20  

From what I read you should go with the highest hths you can get. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1190348&page=2
I still would like to know  how a modern 40w compares to the multigrade oils. From what I experienced there is a direct correlation to how hot the oil gets and outside temperature so in a hot 100+ degree day the oil is going to be 15+ degrees hotter than it would be when operated under the specified max air temperature for a 20w50 oil (85f). Would a modern 40w still perform better than a 20w50 or the like in those high heat conditions? From what I read on the pelican forum the Porsche guys will run 40w on Porsches that were made up through the late 90's (the last of the aircooled).

[airkooledchris]

I still run straight 40 weight Kendall in the summer months. It used to be out of habit, but anytime ive switched to other brands/grades/etc ive always ran into some issue that I didn't have when I switched back to Kendall 40W. Not exactly a scientific method, but it works for my bus and that works for me.

[Hippie]

From what I read you should go with the highest hths you can get.

Yeah, if you can get a super high HTHS and still have an appropriate KV. I wouldn't run 20W-50 in my truck that specs 0W-20 in order to get the higher HTHS viscosity. Enough is enough, is all I mean.

I still would like to know  how a modern 40w compares to the multigrade oils. From what I experienced there is a direct correlation to how hot the oil gets and outside temperature so in a hot 100+ degree day the oil is going to be 15+ degrees hotter than it would be when operated under the specified max air temperature for a 20w50 oil (85f). Would a modern 40w still perform better than a 20w50 or the like in those high heat conditions? From what I read on the pelican forum the Porsche guys will run 40w on Porsches that were made up through the late 90's (the last of the aircooled).

It (the 40 weight) might. It will almost certainly shear less and hold its viscosity in use. But will it make up for possible additional wear during warm-up than a multi-grade? Even a 100 degree F day is cold to your engine that likes 200F, when you start it up. If the temperature stays up there I'd go ahead and use it, but unless you're towing a trailer in the summer, I don't know if there is any overall gain to using the straight weight. You could have a series of summertime UOAs done with each and see if there is any difference in how the engine might be wearing.

cheers,
Rob

[reluctantartist]

Hey Chris,
What were the issues you had with multiviscosity oil? What are the temps you run 40 weight?

[72Hardtop]

Don't forget...the multi visosity oils of 40 years ago are not like those of today. Their (modern multi viscosity oils) ability to resist breakdown is far surperior. That was primarilary the big reason why single grade oils were still recommended back 30+ years ago. Also the new requirements for lower ZDDP levels don't pertain to all oils on the market, only those that have the star burst symbols. As for which oils have the needed ZDDP...Buyer beware.

One other thing with regards to ZDDP. More is not better. Too much will have a negative impact. I believe the recommended level for ACVW flat tappets is in the range of .10-.15

[72Hardtop]

I still run straight 40 weight Kendall in the summer months. It used to be out of habit, but anytime ive switched to other brands/grades/etc ive always ran into some issue that I didn't have when I switched back to Kendall 40W. Not exactly a scientific method, but it works for my bus and that works for me.

That oil does not have the needed levels of ZDDP. Read:
http://www.conocophillipslubricants.com ... 20MO%20(Ti)%20TDS%20Web.pdf|

[Hippie]

Right. Too much ZDDP will actually increase overall engine wear and corrosion. I believe 2000 ppm (0.2%) is the maximum for long term service for a detergent oil, and probably anything more than about 0.11-0.15%  will have no further effect on cam lobes and flat lifters past the relatively short cam break-in period. I have had no issues running 0.8% SM oil in my stock VW 1600, but did use a little ZDDP booster in the very first oil charge when the engine was new.

[airkooledchris]

Hey Chris,
What were the issues you had with multiviscosity oil? What are the temps you run 40 weight?

Unless im driving loaded to the gills for extended periods of time, my oil temps are usually really low - under 200*.


Coming home from Maupin last year I did hit 260* which freaked me out a bit, even though it was the first time I had seen such numbers.
When I got back home I tried switching over to Mobile 1 synthetic and I swear that every little oil leak turned into a medium sized puddle with that stuff.
I saw the same with other multigrades that I tried running previously. (but had changed a BUNCH of seals recently and thought I might be able to get away with it then)
The engine would also seem loose, for lack of a better word, with the lower/mutiviscosity oils. It just didn't *sound* right, if that makes sense, like there was more rattling type sounds coming from it overall. With the straight 40 weight ive always seen good oil pressure/temps in most driving conditions and weather. Until just recently I would run it all winter as well (Winter being 45 degrees) - with a operational thermostat in place to make sure everything warms up as quickly as possible. I also try to always start driving as soon as I fire it up, and drive gently while it comes up to temp (don't let it sit there idling with that heavy cold oil for long)

Im always willing to try something else though, so ill give the brad penn or whatever oil a shot and just see how the bus likes it. If it does I might go try some of that Quaker State Defy next and see if I can't get the ZDDP some claim is important AND much cheaper oil (we just got our first Wal-Mart!)

[Hippie]

I'm not a Mobil 1 fan for any engine. A lot of folks seem to have good luck with it, but to me it seems to make engines noisy, leaks all over, and the iron numbers (probable wear metal) run too high in too many of the used oil analyses that I've seen.
And then there was that big fiasco several years ago where Mobil 1 apparently failed the sequence IVA valvetrain wear test oils have to pass in order to get API approval, and the other oil makers jumped all over that. A fluke? Maybe.
(I use good old Valvoline Synpower in the daily drivers because it usually does so well in the analyses and Sequence IVA.)

[Amskeptic]

I'm not a Mobil 1 fan for any engine. A lot of folks seem to have good luck with it, but to me it seems to make engines noisy, leaks all over, and the iron numbers (probable wear metal) run too high in too many of the used oil analyses that I've seen.
And then there was that big fiasco several years ago where Mobil 1 apparently failed the sequence IVA valvetrain wear test oils have to pass in order to get API approval, and the other oil makers jumped all over that. A fluke? Maybe.
(I use good old Valvoline Synpower in the daily drivers because it usually does so well in the analyses and Sequence IVA.)

I like decent ol' dino oil . . . it works FINE!!!!!!!!!!!!!!!!!!!!!!!
TorturedLittle1600HappyStill

[Hippie]

The primary advantage of synthetics is cold start-up flow and oil life between changes. There isn't that much difference anymore between dino (group II and II+) oils and most synthetics which are group III (start as mineral base stock and are more highly refined) and often blended with a little group IV and V.

[Bleyseng]

I prefer not to use Mobil 1 in my vintage VW's. I did use Mobil 1 in my 04 1.8T as VW had a service bull. and recommended Mobil 1 0/40wt with a bigger oil filter due to the Turbo coking up the oil if it was straight dino.

[Hippie]

^^^ M1, 15W-50 was the only one I liked on the Bus, but it leaked so badly it was basically unusable.