Castrol 5W40

[PanzerSD]

I switched to synthetic oil today, and I noticed a number of things.

First off was the higher HOT oil pressure. I used to be at about 1.5bar at an 80 degree idle now I'm at almost 2.0bar. looks good to me.
The engine seems to rev faster, but that might be in my head.
It's QUIETER! I noticed a marked decrease in the usual clatter that my engine gives off.

Is it all in my head???

oh yeah, one thing I noticed while I was changing my oil. Cold Syn 5W40 is thinner than HOT 15W40 ...coupled with the slightly higher oil pressure I have to say WOW!

I'm guessing it's Castrol TXT 505 01 5W-40?

[PanzerSD]

Uhhhh... I guess, black bottle, bought it at a VW dealership

Castrol Syntec 5W40

[barry123400]

Your idle is probably a little higher with thinner oil. That gives a slight increase in oil pressure. I found it interesting as well that the cold synthetic was thinner than the hot 15-40 dino. It was something I had suspected but not known. As soon as it is practical temperature wise I would increase the viscosity of the oil.

[vstech]

Um, how are you determining that it is thinner? are you heating the oil and measuring it's pour speed? surely you are not touching hot oil... also is the hot 15W40 clean or dirty?
5W40 cold should be plenty thick at room temp, certainly thicker than hot 15W40...
I see no problem using it in warm weather.
John

[uberwgn]

Originally Posted by ForcedInduction

I'm guessing it's Castrol TXT 505 01 5W-40?

It sounds like he bought the Syntec in the black bottle, typically found at Autozone. That oil is certified against MBz 229.3.

Per API spec, an xW-40 oil must have a certain viscosity within the designated range. Many seem to be totally lost on what the xW portion of the label really means...it indicates how easily an engine will turn at low temps relative to another oil. A cold crank simulator and rotary viscometer are used to determine an oil's xW rating.

Remember:

[barry123400]

My prime thrust with the viscosity issue is that these are on average older engines with fairly large clearances. Or lets say clearances that are now greater than original specs at least. I just suspect they have normally opened up somewhat with wear .
I do dislike the time to establish total circulation and coverage with heavier viscosity oils as well. Some effort was made years ago to prelube by external devices. Or spin up the engine prior to starting it.
Clearances especially when cold may be excessive or just too large and difficult a loading area for thin oils to cushion. It probably becomes a personal beliefs thing in the end.
I know I want to see a good coating on the piston walls. Then there is the old story that most wear occurs at startup. Perhaps it is impossible to balance all these component parts.
Believe it or not I am open to ideals. Something might be wrong overall anyways as these engines should go a million miles or close to it in my opinion before needing a rebuild. . I have to wonder what an oil sample lab would recommend to increase the 240d engines practical life span. I have to suspect it would be even more frequent oil changes. A knowledgeable automotive lubrication specialist might have a suggestion as well. I also have read where viscosity stabilizers built into the multi grade oils start to wear out or deteriorate with milage. I wish it all was more clear cut.
One tangably example though. Older volkswagon diesels will have much greater mechanical noise on 10-30 than 15-40. In fact you can really hear the difference. These were older indirect diesel injection engines as well.
What is going to make me rethink all of this is the local availability of dino oils in bulk at pretty cheap prices with the highest recent diesel ratings and approval from the various diesel manufactures on the labels. If I can lower an oil change price to about 5-6 dollars or so on the old 123s I might consider a 1500 mile change out with the filter every second change.
The really unresolved problem remains though. Can someone design a cost effective starting aid for these older 123 diesels in really cold weather? I have not even seen one but these aftermarket high speed starters seem to be quite a help from the little I have heard. If you have to use your 123 in the winter one of them might be worthwhile. In combination with the synthetic oil they might get you running when no block heater is available. I also feel if your compression is not pretty high you are flogging a dead horse to some extent.
I really know very little in this area. My observation skills are just too weak. I have developed no really fixed position. The synthetic tends to always look better on paper.

[uberwgn]

Barry, you make valid points. The thrust of my commentary is aimed at the modern cars, not the W123 era machines. However, I do know several folks with W123 diesels that are getting excellent results running Shell's Group III diesel oil which you can buy by the gallon at WallySmart for ~$15 or so. It's kind of a no-brainer to me...even for the older cars.

[greasybenz]

wait arent VW 505.01 oils group 3 synthetics? I had used ELF 5w40 505.01 in my 87 300D and there was alot of lifter tick with the oil in the engine.

Now im on Amsoil 15w40 synthetic and the engine is smooth at idle. No lifter ticks!

[tarbe]

Originally Posted by PanzerSD

oh yeah, one thing I noticed while I was changing my oil. Cold Syn 5W40 is thinner than HOT 15W40

I suppose you ran both oils through a viscometer?

Seriously, this is simply not even close to being correct.

Depending on your definition of hot and cold...most 15W-40 oils are around 15.5 cSt at 212F, while a synthetic 5W-40 will probably be closer to 200 cSt at 60F.

[PanzerSD]

Originally Posted by vstech

Um, how are you determining that it is thinner? are you heating the oil and measuring it's pour speed? surely you are not touching hot oil... also is the hot 15W40 clean or dirty?
5W40 cold should be plenty thick at room temp, certainly thicker than hot 15W40...
I see no problem using it in warm weather.
John

the concern isn't it being thick enough at high temps, it it was 5w40 dino I would DARE run that any warmer temp than about 0c ambient because the thermal viscosity breakdown would mean that it'd be wearing my engine out with a lack of lubricity at those ambient temps. I'll trust synthetic light oil at any temp simply because it's formulated to be.

that said, what should my oil change intervals be now? sooner or later? Synth isn't outrageously expnsive, but it's more than I car to spent too often.

I noticed the viscosity difference when I was pouring the still hot USED 15W40 dino into my waste tank. it didn't flow much faster than clean 15W40

BUT

my case of Syntec5W40 had been sitting in my car all day and was about -22ambient and it was pouring thinner than HOT 15W40. Also, after driving it my cold idle oil pressure goes up to 3 bar when I start then it drops ALOT quicker (because it's thinner) to normal idle pressures, of what I was expecting 1.5bar but was elated to see almost 2bar. worst case scenario would have been that my engine was too loose to run light synthetic oil witout a DROP in hot idle oil pressure.

(waste tank: I take my used oil to work and put it in the waste oil furnace )

[PanzerSD]

Originally Posted by tarbe

I suppose you ran both oils through a viscometer?

Seriously, this is simply not even close to being correct.

Depending on your definition of hot and cold...most 15W-40 oils are around 15.5 cSt at 212F, while a synthetic 5W-40 will probably be closer to 200 cSt at 60F.

I used an old Zahn cup. Hot 15w40 dripped at 2 drops per second and the cold 5w40 dripped at 4 drips per second (just as a comparison)
an old painter technique from the days of Laquer paint

whether it's relevant to anything, I don't car, it's just someting I observed.
if you shake a bottle of 15w40 and a bottle of 5w40 you can tell that the 5w40 is inhrently going to be thinner...commom sense..:fork_off:

[barry123400]

Originally Posted by greasybenz

wait arent VW 505.01 oils group 3 synthetics? I had used ELF 5w40 505.01 in my 87 300D and there was alot of lifter tick with the oil in the engine.

Now im on Amsoil 15w40 synthetic and the engine is smooth at idle. No lifter ticks!

Volkswagon diesel has been sythetic only since the end of 99 I believe and they are direct injection engines. The earlier indirect injection engines and earlier tdi engines always used dino oil around here. I think even the first 99 1/2 tdis were still on dino as well. Volkswagon wants euro speck synthetic for the last few years as well I believe. They claim our synthetics do not cut it for their cars. Getting like a giant puzzle.

[uberwgn]

Originally Posted by barry123400

Volkswagon diesel has been sythetic only since the end of 99 I believe and they are direct injection engines.

True, if you consider Group III to be synthetic.

VW direct injection motors were first introduced to the NAmerican mkt in 1996 in the Passat B4 body. They did mandate an upgrading of the oil spec to "synthetic" per the April 1999 service bulletin. Keep in mind, the Castrol Syntec (topic of this thread) is of course Group III.

[uberwgn]

Originally Posted by greasybenz

wait arent VW 505.01 oils group 3 synthetics?

There was a tweaking of the 505.01 spec this past summer. There are a few 505.01 oils that are now Group IV/V blends.