w126 420SEL oil pressure question
 

I did the first oil change on this car since I bought it, and I'm nervous about something...
the PO used 10w40 Havoline and Fram filter at an unknown change interval. The pressure gauge would read "3" at speed and under load, and fall to right around 2 at idle or coasting

I filled it with 15w40 Delo and a Wix filter today, in 60 degree weather. The pressure gauge pegged at 3 and stayed that way until I got the car up to temp, then it only fell to 2.5 at idle or coasting.

I did note that the Delo seems noticeably more viscous than the 10w40 Castrol GTX that my wife's Jeep uses. Is it just an oil difference, or have I screwed something up?

BTW, the car has 172xxx miles.

Oil pressure sounds OK to me!!

good...I would hate to be the one who screws up the car. I'm trying to be thrifty by doing some of my own maintenance and my worst fear is blowing up one of the cars due to an "oops"

I don;t want to upset you, but
 

The biggest problem is chain wear and chain guide breakage causing engine destruction. There are many posts about this and instructions on how to replace the chain and guides.

Don't worry davestlouis, your car runs better than so many cars in its class. My 560SEC 1989 read 1 or less oil pressure when it's hot.
Another thing that your car engine looks in a great shape, so always take care of the oil and filter. I recommend MANN filter for your car NOT the original one because in Kuwait the original filter is mand in India.

Hey, Dave,

My previous Benz was the W126 420, and I used that same oil (though with a Mann or Knecht filter). On my earlier changes down here in NO -- hot climate, and that's putting it mildly -- I'd used 20W50, and had a hot pressure at idle of 1.8. When I went to 15W-40, which you'd think would be thinner, my oil pressure settled at 2.2.

The 15W-40 Delo is one of the super-dino oils, with extra additives to handle diesel contaminants. It does fine on a gas engine like the M116. As long as your gauge pegs at 3.0 when you start the car cold, and rises from that idle setting to 3 when you pass about 1500 rpm, you're OK.

Paul, thanks for the input. I find myself liking this car more and more, and I'd like to keep it around for awhile. Dave

Please inform me!What is Delo oil?

I'm no expert by any stretch, but Delo is a 15w40 diesel-rated motor oil, available at AutoZone, etc. Delvac 1300 is similar, and Castrol makes a Tection oil...Valvoline True Blue seems to be their contribution to that particular market. The service dept at the dealership has Pennzoil in 15w40 that is not specifically designed for diesels, but at retail outlets heavier weights of oil are tricky to find.

Chevron Delo . . .
 

. . . (short, I think, for Diesel Engine Lubricating Oil) is also a tremendous bargain. In my area, New Orleans, a 4-qt. jug can be bought at Autozone for about 7.00, maybe a few pennies less at Wolde-Mart. Less than 2 bucks a quart for a superb oil? A bargain indeed.

If you want to put diesel-rated oil in a gas car, look on the bottle to be sure it is rated for both gas ("S") and diesel ("C"). I'm not sure a strictly diesel-rated oil is right for a gas engine; anybody know?