Thin and thick.....

[ac_tc]

Ok so we have dr Haas who convince us to use a thin oil
wich increases the oil flow att higher engine speeds but lowers the pressure at lower speeds- sound ok to me but..
What if my engine pops the valve at 1700 rpms and almost all
the time runs at that speed mostly towing, is then the reasoning ok?
Wouldnt it be better to have an oil thick enough to build pressure
and be on the verge for popping the valve?
Then ill get bot volume and pressure.
I understand dr H´s reasoning when it comes to high revving ferraris which doesent produce much of low speed torque anyway
and when working is at higher speeds but in my 5.9 l mopar
v8 wich usually is at highest possible gear and seldom see´s
anything higher than 2000 rpm´s?

 

[Hokiefyd]

What do you mean: "pops the valve at 1700 rpms"?

Either way, I see no need to run anything other than what Dodge recommends for your Durango, which is probably 10w30, even in Europe. Even for towing, I'm not sure I see the benefit of a 40wt oil, but it's probably not hurting anything either. You might gain a bit of power and mileage on a 10w30, but possibly not enough to tell either way.

 

[Steve S]

Dr Haas hasn't convinced me of anything . I am so amazed hoe internet readers believe anything.

 

[SLCraig]

I'd be afraid to know how much it costs to fill a 5.9 Durango in Sweden.

I'd just use a 10w30 in it too honestly. Or whatever its called for.
I'm pretty sure its very challenging to kill those 5.2 and 5.9 engines. They last forever.

 

[NateDN10]

Originally Posted By: Hokiefyd
What do you mean: "pops the valve at 1700 rpms"?

I believe (based on this sentence: "Wouldnt it be better to have an oil thick enough to build pressure and be on the verge for popping the valve?") that he's talking about the bypass valve.

 

[NateDN10]

I'd stick with 10w30 or 5w30 as well.

 

[demarpaint]

Why not get an oil temp gauge, and a pressure gauge and post readings? While the engine is good and hot under the conditions it is most driven, with the oil you'd like to test. Then take temp and pressure readings, at idle and while in use. Log the readings, post the readings here and maybe some like CATERHAM, Doug Hillary, or one of the other people in the know will give their suggestions and recommendations. It will eliminate a lot of guessing, bashing, and give you useful information vs. a lot of opinions and guessing.

 

[webfors]

30 weights are the universal viscosity. Not too thick, not too thin, just right for those of us stuck in the thick/thin dilemma.

 

[Steve S]

Originally Posted By: demarpaint
Why not get an oil temp gauge, and a pressure gauge and post readings? While the engine is good and hot under the conditions it is most driven, with the oil you'd like to test. Then take temp and pressure readings, at idle and while in use. Log the readings, post the readings here and maybe some like CATERHAM, Doug Hillary, or one of the other people in the know will give their suggestions and recommendations. It will eliminate a lot of guessing, bashing, and give you useful information vs. a lot of opinions and guessing.
I would put my money and engines life on
Doug H's. input as his input is fact combined with experience, not just opinion.

 

[Bruce T]

Dr Haas has challenged traditional thinking in a good way, but he should be labelled, "For Entertainment Purposes Only," since his circumstances aren't typical. Go with the Owner's Manual or oil temp/pressure gauges. You can always run a thinner oil, but stay within the recommended grade.

 

[demarpaint]

Originally Posted By: Steve S
Originally Posted By: demarpaint
Why not get an oil temp gauge, and a pressure gauge and post readings? While the engine is good and hot under the conditions it is most driven, with the oil you'd like to test. Then take temp and pressure readings, at idle and while in use. Log the readings, post the readings here and maybe some like CATERHAM, Doug Hillary, or one of the other people in the know will give their suggestions and recommendations. It will eliminate a lot of guessing, bashing, and give you useful information vs. a lot of opinions and guessing.
I would put my money and engines life on
Doug H's. input as his input is fact combined with experience, not just opinion.


That's why I mentioned him, the words facts combined with experience sums it up perfectly. Doug is also a big fan of approved oils and mfg recommendations. I consider him a wealth of knowledge, an asset to the board, as well as a friend!

 

[lomez]

depends. To me, it depends on how long you let the oil warm up (driving with limited load) before really placing large loads on bearing, as from towing. The thicker grade oil will flow just fine, and probably provide slightly better shear protection at or above 212 degrees. Until then (lower temps), I would have concerns as to whether the thicker oil is getting where it needs to go.

IMO- It probably doesn't matter a lick. If it were me, I'd use an oil with the best shear protection at high temps (while staying within manufacturer's recommendation in terms of viscosity), AND make a point to never tow until the oil is up to operating temp.

 

[aquariuscsm]

Isn`t the golden rule to use the "thinnest" grade possible to give you the best protection? For example,if your car specs 5W30-20W50,wouldn`t 5W30 be the best,with 5W20 being too thin,and 10W30 being unnecessary?

 

[demarpaint]

Doesn't a 98 Durango call for 5w30 oil?

 

[CATERHAM]

ac_tc, if you're running a 40wt oil in a 30wt application you very well could be running with the oil pump in by-pass mode at elevated rev's even with the oil as hot as it ever gets; not a good thing and clearly counter-productive.
Running the spec' oil grade, with the engine oil up to normal operating temperature the oil pressure will be below the by-pass setting. How light an oil you can use is based on the minimum OP spec' for your engine. In light duty applications one can frequently run a grade lighter than spec' without testing the min' OP spec'.

Another point that Dr. Haas makes is to run a high viscosity index synthetic oil if you can afford it such as what you get with most 0W-XX and some 5W-XX oils particularly if you are doing a lot of cold starts and relatively short runs. The lighter the oil is on start-up the better which is why Dr. Haas runs 0W-XX oils even in the State of Florida.

 

[mechtech2]

I still am not sure of what 'pops the valve' is supposed to mean.

Dr. Haas only states that thin oil is perfectly suitable if the temperatures are also commensurate [not too hot].
This is what the oil mfrs and car mfrs say.
No new news at all.

Except, Dr. Haas does it in MANY words!

 

[Ken2]

Dr. Ali E. Haas is a cosmetic plastic surgeon who probably knows more about skin oil than motor oil. I've never seen anything in his writing about the hydrodynamic wedge of oil that builds up in rotating journal bearings which is the real reason the oil holds the parts apart.

Other things equal, higher viscosity oil has higher film strength. This means greater protection under heavy load. The rate of oil pumped to contact points inside the engine is only important for non-rotating contact points...wrist pins, cam followers, etc. While ample oil is important, adequate film strength is also important.

I'd stick with the recommended oil viscosity or one grade higher for the engine that is run very hot & heavy.

 

[CATERHAM]

Originally Posted By: mechtech2
I still am not sure of what 'pops the valve' is supposed to mean.

It's the pressure release valve that's on all oil pumps.
It's activated if you rev' an engine too high with cold (thick) oil and at operating temp's if you're running an oil much thicker than necessary.

 

[electrolover]

Originally Posted By: webfors
30 weights are the universal viscosity. Not too thick, not too thin, just right for those of us stuck in the thick/thin dilemma.

 

[ac_tc]

Ok.
Pops the valve- open bypass valve on oilpump.
Still a 40 hdeo gives me with warm engine and oil (90/110 degC)
an oilpressure (slightly below 3 bar) thats on the edge of popping my bypass
at my typical running speeds.
Of course it wouldnt be great at higher engine speeds
but the question was if that wouldnt be optimal
for my use. Note that the engines runs "semi lugged" almost all
the time (cruises at 1500-1700 and sometimes during climbs 2400)
If i follow dr H´s rec ill use an oil that gives pop off att 4600
and thats extremely seldom my engine is at that speed.

By the way it costs about 1400 skr or 225$ to fill it with gas
and the oil i use costs 7$/ liter but a liter of Mobil 1 5w40
nets around 22$.....(i use around 40-60 liters a year, so i dont mind getting it in 20 liter cans)