Is 0w-40 always better than 5w-, 10w,- and 15w-40?

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Hi!

In general, why would one ever choose a 5w-xx, 10w-xx, 15w-xx or 20w-xx over a 0w-xx, if a 0w-xx in your viscosity grade is available?

More specific, can I, under almost all circumstances, safely change from a 5w-40 to a 0w-40?

The reason I'm asking, is that I have an Mercedes Benz 420SE (V8) from 1990 with 110k miles, that I'm wondering about changing both brand and viscosity grade on. I bought it last year, and the service manual states that it's been running on 5w-40. It has some slight valve train chatter when warmed up, but it's not bad, the cams were new two years ago. It's an SOHC design with hydraulic tappets. It's currently using around 0.6qt per 1000 miles, but there is no blue smoke or visible leaks.

I'm currently using a 5w-40 no-name rebranded oil that meets the latest MB 229.5 spec, but I want to see if Mobil1 0w-40 New Life may dampen the valve chatter a little when the engine is hot. Obviously not because of the change in cold viscosity, but just because the Mobil1 may be a better oil. The alternative is Mobil Super 3000 5w-40.
 
Hi,
Yes, of course, a 0w40 can take place of a 5w40 with no issue. Will it quiet down your engine, that's not impossible, since it will probably stand its grade better at high temps.
People who would still buy a 5w40 or 10w40 even knowing that are : people who are afraid and prefer keeping with the manufacturer's advice, and people who shop by price, as they would take the cheapest "good enough" one
 
I think everyone would agree that M1 0w40 is the best 40 weight product available from Mobil.

That's exactly what I would use.
 
Thanks for your input! I was glad when I read the first two comments, but then confused again after reading the 3rd and 4th.

I've probably spent about 30 hours the last months reading about oils. As far as I can understand, there is no advantage what so ever to using an oil that is thicker at startup, hence my question. I've been recommended everything from 0w-40 to 20w-50 when I've asked. I've even bought a bottle of ZDDPlus that I've concluded that I won't use. The manual from 1990 recommends 5w-40 and 10w-40 in my climate, and the spec was MB 229.1, which is superseded by 229.3, and later 229.5, which MB says is backwards compatible. The only oils in Norway that meet 229.1 directly is cheaper 10w-40 and 15w-40s, including the Mobil Super 2000 (which I have in my second car, 190E).

A (not so) fun fact: a qt of 0w-40 New Life costs $36 at gas stations in Norway. A gallon costs $70 at the cheapest store.
 
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Originally Posted By: Teddyen
I've even bought a bottle of ZDDPlus that I've concluded that I won't use.


How did you arrive at that conclusion?
 
0w for light to moderate conditions, 15 /20w for severe (turbo, shared sump tranny, air cooled etc). Straight wt offers stability and w-rated versatility as I look at it.
 
I'd add that, as you're consuming 0.6qt / 1000mi and hearing your valves, you probably have some sludge/varnish in your engine, and that the Mobil 1 could help cleaning. That can be a good point, or a bad one. Sometimes it's better to leave the filth where it is, than risking clogging something... what do you'all think about that ?
 
Originally Posted By: Teddyen
More specific, can I, under almost all circumstances, safely change from a 5w-40 to a 0w-40?

As long as it also meets the required MB spec it should be fine, an improvement actually. And Norway has some cold that would warrant going to a 0W- anyway.

I use Castrol 0W-30 in my BMW year round when the manual recommends 5W-30. The 0W-30 meets the BMW LL-01 spec. Have used it for about 10 years and 90,000 Km. Can't see any reason not to. I too have cold starts.
 
Originally Posted By: Dyusik
0w for light to moderate conditions, 15 /20w for severe (turbo, shared sump tranny, air cooled etc). Straight wt offers stability and w-rated versatility as I look at it.


Odd, given that many forced induction engines from Porsche and Mercedes both spec M1 0w-40. I also run it in my M5.
 
Originally Posted By: Dyusik
0w for light to moderate conditions, 15 /20w for severe (turbo, shared sump tranny, air cooled etc). Straight wt offers stability and w-rated versatility as I look at it.


0w40 for winter on Nordkapp.....

Normal use at lower Norway 5w40 or 10w40.....its just N/A engine
wink.gif


5W40 for normal use.... Aircooled or turbo filled engine...(because I prefer synthetic for that)....
 
Two questions in this thread...

1) Is 0W40 always superior to 5W, and 10W (won't mention the 15W for time being)...answer to the "always" part is an emphatic no.

The make-up for a 0W40 can include lots of VII and PPD, whcih can be a risk to varnish and viscosity loss in service.

2) M1 0W40 specifically, which is probably one of the best oils on the planet.

If M10W40 fits in your budget, have a crack at it, but to maximise the value of your spend, run it as long as the manual lets you run it.
 
It rarely gets below -10C here, I primarily want to try the M1 0w-40 because it seems like it has a very good reputation.

Originally Posted By: GuillaumeG
I'd add that, as you're consuming 0.6qt / 1000mi and hearing your valves, you probably have some sludge/varnish in your engine, and that the Mobil 1 could help cleaning. That can be a good point, or a bad one. Sometimes it's better to leave the filth where it is, than risking clogging something... what do you'all think about that ?


I believe the engine is fairly clean: I took off the valve cover last summer, and everything was fine and dandy. The vehicle have probably used synthetic oils for many many years. I've changed oil three times the last 6000 miles. The first time when I bought it, just filled up with Castrol GTX 10w-40 until I realized that it had run on 5w-40. Then I changed again, this time to 5w-40. After 1000 miles I realized that the engine had been running on 7 "and a half" cylinders since the last oil change due to a loose spark plug wire. I had also added a mild cleanser (Wynns Hydraulic Valve Lifter Consentrate) in the oil during this period. I changed the oil immediately when I found out about the loose spark plug wire, the oil smelled strong of petrol. The wire and plug was also changed, the plug was pitch black. My other plugs was completely normal when I changed them.

The engine has however been running very cold for a long time, as I discovered that the thermostat was full open all the time this winter. The last owner probably didn't notice it, and I don't know how long it's been like that. The engine never got above 70C in the winter until I changed it, and took half an hour to get up to this temperature. Now it takes five minutes to get to 90C, where it stays.

The engine is smooth running and very responsive, but with rough warm starts. Fuel consumption is spot on the specs from Mercedes, can't complain.

Originally Posted By: Shannow
Two questions in this thread...

1) Is 0W40 always superior to 5W, and 10W (won't mention the 15W for time being)...answer to the "always" part is an emphatic no.

The make-up for a 0W40 can include lots of VII and PPD, whcih can be a risk to varnish and viscosity loss in service.

2) M1 0W40 specifically, which is probably one of the best oils on the planet.

If M10W40 fits in your budget, have a crack at it, but to maximise the value of your spend, run it as long as the manual lets you run it.


Thanks for a very clear answer. I'm now leaning towards trying the 0w-40, as the cost isn't really a problem, and it seems that it won't harm my engine. I find oils to be an interesting topic, I'd like to learn more about how 10w-40s and 15w-40s can be better than a 0w-40.

Originally Posted By: Ramblejam
Originally Posted By: Teddyen
I've even bought a bottle of ZDDPlus that I've concluded that I won't use.


How did you arrive at that conclusion?


As far as I know, it's more important with flat (dome shaped) tappets. I believe I have sliding cylinder shaped (?) hydraulic tappets on my SOHC, together with stock cams and stock valve spring pressure. I don't think I need any more than what's already in the oil I use (around 1000ppm). I guess that I trust M1 to make a great oil, and that I can't really improve on it by adding stuff on my own, but I don't really know for sure. If anything, I'd only add enough to rise the levels to around 1400ppm, but I don't feel comfortable with it, as I don't really know how this will affect the rest of the oil's properties. Feel free to educate me!
 
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You definitely do not need more ZDDP. Many guys in the bimmer world use M1 0w-40 in their much higher revving engines which also use non-roller HLA's. It has more than enough ZDDP for all but the wildest flat tappet pushrod mills, which would have massively heavier springs due to the valvetrain mass.
 
M1 New Life is not really good buy in Europe at all. For same price you can get Castrol Edge Ow40 that's real PAO, New Life is simply overpriced for Hydrocracked Gr.III oil. Not saying it's bad, just Castrol is better. Cheaper alternative to those two would be Shell Helix Ultra 5w40, very well priced, and with the same approvals.
 
Originally Posted By: chrisri
M1 New Life is not really good buy in Europe at all. For same price you can get Castrol Edge Ow40 that's real PAO, New Life is simply overpriced for Hydrocracked Gr.III oil. Not saying it's bad, just Castrol is better. Cheaper alternative to those two would be Shell Helix Ultra 5w40, very well priced, and with the same approvals.


M1 0w-40 is PAO-based again.
 
Originally Posted By: chrisri
Don't want to start this again, but New Life is still marketed as SHC in Germany...


Yup, I know it is. Mobil may continue to market it that way too in case they decide to change the formula again.

Castrol 0w-40:
http://msdspds.castrol.com/ussds/amersdsf.nsf/Files/013CC9B6FF64053680257CA50058D02E/$File/301855Castrol%20EDGE%200W-40%20A3_B4.pdf

Shows Dec-1-ene, trimers,
hydrogenated CAS 157707-86-3 @
Mobil 1 0w-40:
Shows Dec-1-ene, homopolymer, hydrogenated CAS 68037-01-4 @ 50 -
So it would appear that despite how each are marketed, the Mobil product has more PAO in it than the BP product.

The CAS # for the Mobil product is shown to be PAO here:

http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/257881/MSDS'_and_CAS'#Post257881

by poster Molakule. He lists a # of CAS #'s for PAO in that thread however the one for the BP product does not show up. Through a bit of googling, I found this page:

http://www.hopaconsortium.com/index.php/substances

And under the heading "Polyalpha Olefins", there is the CAS # for the product BP is using.
 
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