Which Viscosity of Oil?
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Super Member
Joined: Aug 2005
Posts: 591
Likes: 9
From: Covington, WA
'96 SL600, '05 S55 AMG, '06 C230
Which Viscosity of Oil?
One of the charts that has always seemed baffling is the one that compares viscosity of oil to outside temperature. Attached is the chart from the 2006 MBZ Factory Approved Service Products bulletin.
Assuming the minimum outside temperature is 50ºF, then the chart recommends that any viscosity oil can be used - anything from 0W-30 up to 20W-50. This seems like a pretty wide range of viscosity weights. Even temperate West Coast temperatures would allow for a pretty wide range of viscosity choices. Are there any 'rules of thumb' in further determining which is the best viscosity for any given situation?
Curiously, the Owner's Manual for my '96 SL600 does not specify a viscosity; only the quantity. The only reference in the entire manual is on page 146, where it simply says "Recommended engine oils" beside the quantity needed
Assuming the minimum outside temperature is 50ºF, then the chart recommends that any viscosity oil can be used - anything from 0W-30 up to 20W-50. This seems like a pretty wide range of viscosity weights. Even temperate West Coast temperatures would allow for a pretty wide range of viscosity choices. Are there any 'rules of thumb' in further determining which is the best viscosity for any given situation?
Curiously, the Owner's Manual for my '96 SL600 does not specify a viscosity; only the quantity. The only reference in the entire manual is on page 146, where it simply says "Recommended engine oils" beside the quantity needed
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Joined: Mar 2006
Posts: 4,278
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From: San Jose area
'19 E63S sedan
For engines lubricated with dino oil, you can pick any viscosity range that covers your temperature range. It doesn't hurt to go wider, but as long as you're sure there won't be a colder snap than you expected, you'll be fine.
However, since 1998 MB has required synthetic oil so this is becoming less of an issue every year. Synthetic oils inherently have less viscosity change with temperature, and all of the approved ones have a cold viscosity of 0W or 5W. The hot viscosity is either 30 or 40, but only 40 hot oils are approved by AMG so I would go with a 0W-40 or 5W-40 in any Mercedes engine that used synthetic oil. But again, with synthetics selection is based on approved oil type and viscosity comes along for the ride.
However, since 1998 MB has required synthetic oil so this is becoming less of an issue every year. Synthetic oils inherently have less viscosity change with temperature, and all of the approved ones have a cold viscosity of 0W or 5W. The hot viscosity is either 30 or 40, but only 40 hot oils are approved by AMG so I would go with a 0W-40 or 5W-40 in any Mercedes engine that used synthetic oil. But again, with synthetics selection is based on approved oil type and viscosity comes along for the ride.
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Joined: Jun 2002
Posts: 7,263
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From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
I'm wondering about this myself.
Currently Kragens has Valvoline Synpower on sale for
a buck a quart.
A quick look at the chart at http://www.whnet.com/4x4/oil.html
seems to show that the 5w-30 and the 20-50 are both approved for
229.3, which is fine for 2002.
Here in Norcal the weather rarely goes below 23F degrees, which is the lower limit of what recommended for 20-50 and it's summer.
In the past I typically ran 20-50 castrol in other cars with high revving
4 bangers...seemed to burn less oil.
And as my car is a high revving hot running 4 banger with an overdriven supercharger, it seems like 20-50 would be a good thing?
Or, should I go with the 5w-30 with a temp range going all the way down to -13F ? Not likely to get that cold anytime soon around here.
Is there an advantage to either?
Currently Kragens has Valvoline Synpower on sale for
a buck a quart.
A quick look at the chart at http://www.whnet.com/4x4/oil.html
seems to show that the 5w-30 and the 20-50 are both approved for
229.3, which is fine for 2002.
Here in Norcal the weather rarely goes below 23F degrees, which is the lower limit of what recommended for 20-50 and it's summer.
In the past I typically ran 20-50 castrol in other cars with high revving
4 bangers...seemed to burn less oil.
And as my car is a high revving hot running 4 banger with an overdriven supercharger, it seems like 20-50 would be a good thing?
Or, should I go with the 5w-30 with a temp range going all the way down to -13F ? Not likely to get that cold anytime soon around here.
Is there an advantage to either?
Super Member
Joined: Jan 2008
Posts: 508
Likes: 1
From: california high desert
2003 S500, 03 C240, 03 E320, 03 tahoe
switched from mobil
ive also run castrol products in everything until we started buying/maintaining MB's.i was loyal to the mobil 1 0/40 on our E-320 and at 66,000 miles it developed alot of noise on initial cold startup.who knows why,but on our S class i have switched to castrol syntech 10/40 and hope to have 
better longevity on the motor.i will say that i live in the ca high desert and our summer temps can reach 118 f.i dont see the need for a oil that is designed to flow at sub 0 temps.
better longevity on the motor.i will say that i live in the ca high desert and our summer temps can reach 118 f.i dont see the need for a oil that is designed to flow at sub 0 temps.
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 377
From: San Jose area
'19 E63S sedan
ive also run castrol products in everything until we started buying/maintaining MB's.i was loyal to the mobil 1 0/40 on our E-320 and at 66,000 miles it developed alot of noise on initial cold startup.who knows why,but on our S class i have switched to castrol syntech 10/40 and hope to have better longevity on the motor.i will say that i live in the ca high desert and our summer temps can reach 118 f.i dont see the need for a oil that is designed to flow at sub 0 temps.
better longevity on the motor.i will say that i live in the ca high desert and our summer temps can reach 118 f.i dont see the need for a oil that is designed to flow at sub 0 temps.
