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'91 560SEC, '98 SL500
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Hey Guys - I know we have our oil preferences from weight and manufacturer (esp. depending where we live).

But yesterday I found out that Castrol has released their Classic 20W50 oil with added Zinc and Phosphorous which will assist in the prevention of valvetrain flat spots.

For our W126 cars this is a great oil choice and option.

This oil was introduced last year and has been slow to reach all markets, for example here in Texas (unless I was snoozing).. I paid $22 for a 5Qt Jug.

Typically, I add Redline Zinc additive to my oil, so now I do not have to buy this stuff and formulate my own cocktail.

Here is a quickie summary and comparison:

Rotella T5 10W30
Phos = 1159 ppm
Zinc = 1342 ppm

Castrol GTX Classic 20W-50 from their MSDS
Phos = 1200 ppm
Zinc = 1300 ppm

Personally, I like to see 1000ppm Zn or above.

CASTROL GTX CLASSIC | WELCOME | CASTROL USA





Thought I would share.
Yasin
 

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'17 GLS450, '14 GLK250 "Grandpa's Roadster" Project Car, 350SDL (Sold)
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“Sooner or later, everything old is new again.” - Stephen King
 

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91 420SEL, 72 350SL, 99 S600, 05 Ford F-350, 09 C300, 10 Boxster 987, 12 GL450 , 87 560SEL ,05 SL60
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Hey Guys - I know we have our oil preferences from weight and manufacturer (esp. depending where we live).

But yesterday I found out that Castrol has released their Classic 20W50 oil with added Zinc and Phosphorous which will assist in the prevention of valvetrain flat spots.

For our W126 cars this is a great oil choice and option.

This oil was introduced last year and has been slow to reach all markets, for example here in Texas (unless I was snoozing).. I paid $22 for a 5Qt Jug.

Typically, I add Redline Zinc additive to my oil, so now I do not have to buy this stuff and formulate my own cocktail.

Here is a quickie summary and comparison:

Rotella T5 10W30
Phos = 1159 ppm
Zinc = 1342 ppm

Castrol GTX Classic 20W-50 from their MSDS
Phos = 1200 ppm
Zinc = 1300 ppm

Personally, I like to see 1000ppm Zn or above.

CASTROL GTX CLASSIC | WELCOME | CASTROL USA





Thought I would share.
Yasin
BUT OTOH both phosphorous and zinc will poison a catalytic converter. So if you are unfortunate enough to live in one of those states that require an emmision inspection on older vehicles, using a high zinc/phosphorous oil will cost you in the long run - cats for older mercedes vehicles run into the low thousands unless you buy cheap ones that don't work well enough to satisfy the CARB standards. Either way the State wins and your vehicle is soon off the road and in the scrap heap - replaced by an EV. I am lucky enough to be able to scrap my cats and pass inspection when the time comes, so another high zinc/phosphorous oil on the market is good news.

PS Lets not start another oil war fueled by ignorance and opinion.
 

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1985 MB 500sel (Euro)
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1,217 Posts
We do not mind another oil thread when it brings good news such as this. Always good to have a backup.

I got rid of my cats when I changed original exhaust system after 21 years in Virginia. Perhaps a bit premature, but I am assuming Florida has the same rules. Besides, which, my county has is no exhaust tests. For the record, Shell says the T4 which I use has z/p at 1200 ppm of zinc and 1100 ppm phosphorus at the time of manufacture.)
 

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1986/1990 W126
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20,672 Posts
No cats for me, mine didn't come with them. I use classic friendly oil 10x40 with good ZDDP - choices for this weight of oil you've posted are so limited here, good news. I only went 20x50 once. Its 33c here today and has been for a while, I quite like the idea of a heavier summer oil when it gets so hot here.
 

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Good find !!

These levels of zinc and phosphorus are still way below the levels in older oil, so the concern that it will damage the catalytic converter is a baseless concern. Older oil’s had way more zinc and phosphorus and did not damage the catalytic converter’s.

either the shell Rotella or this Castrol are both excellent choices. This Castrol, being a 20 W 50, is best for warmer climates such as Texas where OP lives, California, Florida, etc. for year round usage .

those in the north or colder climates may prefer the shell Rotella 10W-30 during winter.

it is always best to leave a functioning catalytic converter on the car, not only does it keep the resale value higher and allow you to sell it to more states where emission testing still requires a catalytic converter, it also reduces the exhaust smell which can come inside the cabin. So if you have a functioning catalytic converter, leave it alone. If it’s plugged up or dead or damaged, and your state does not require it, then it’s a good time to remove it.
 

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1985 500sel and 500sec 2012 E63 1989 Porsche 911
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6,411 Posts
been happy withbrad penn 20 50 but good to know castrol is up to par now
 
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