Delvac-1 observation

[Dervman]

Not that I'm complaining, but after changing my oil at the weekend to Mobil Delvac-1 5W-40 from Mobil-1 15W-50 my oil pressure is indicating slightly higher on the gauge. Its only about a needle-width's higher but noticable. I didn't change the O-rings on the filter stem (I do that every 3 changes) so I can't explain it by anything I did differently.

Does Delvac have some mysterious thickening quality
I would have thought that going from 15W-40 to 5W-40 if anything the oil pressure would be slightly lower.

As I said, I'm certainly not complaining, just curious

[Brian Carlton]

Andy,

My guess it that the comparison is not valid. The new oil is not "sheared" as much as the oil that has been running for 5K miles, so, it will register higher pressure.

You would need to drain the new oil out and replace it with fresh 15W50 for a valid comparison to the fresh 5W40.

I just read in another benz site, someones thread reguarding viscosity being answered by a race car driver who warned about motor oils with big gaps between viscosity such as 5 - 40, and in particular M-1 15 - 50 that it is a better oil that has closer viscosities such as 10 - 30. I'll have to go back and read it again, but he claims the wider the spread the less lubricating quality!

Any one heard anything about this?

[billrei]

Originally Posted by Dervman

Not that I'm complaining, but after changing my oil at the weekend to Mobil Delvac-1 5W-40 from Mobil-1 15W-50 my oil pressure is indicating slightly higher on the gauge. Its only about a needle-width's higher but noticable. I didn't change the O-rings on the filter stem (I do that every 3 changes) so I can't explain it by anything I did differently.

Does Delvac have some mysterious thickening quality
I would have thought that going from 15W-40 to 5W-40 if anything the oil pressure would be slightly lower.

As I said, I'm certainly not complaining, just curious

Is this reading at idle or at speed? My oil guage pegs itself high at anything much above an idle so I would never notice the difference at speed. If you see a difference at speed I would be worried about your oil pressure.

[Secret Squirrel]

Originally Posted by BusyBenz

I just read in another benz site, someones thread reguarding viscosity being answered by a race car driver who warned about motor oils with big gaps between viscosity such as 5 - 40, and in particular M-1 15 - 50 that it is a better oil that has closer viscosities such as 10 - 30. I'll have to go back and read it again, but he claims the wider the spread the less lubricating quality!

Any one heard anything about this?

If you want several weeks of reading backed by used oil analysis etc, go to www.bobistheoilguy.com forums and search for Delvac 1 and Mobil 1 Truck & SUV (basically the same thing). This 5W-40 oil is tough enough to run 10's of thousands of miles in fleet duty usage. What the gentleman was referring to can be applied to regular dino oil, i.e. 10W-40, but not to the modern synthetics.

I do not personally believe there is a better oil for our vehicles.

If you want a heck of a deal $ wise look for the newly arriving 5 quart jugs of the M1 Truck & SUV that Walmarts are rolling out this week. Right under $20 for a 5 quart jug.

[Brian Carlton]

Originally Posted by Secret Squirrel

If you want a heck of a deal $ wise look for the newly arriving 5 quart jugs of the M1 Truck & SUV that Walmarts are rolling out this week. Right under $20 for a 5 quart jug.

Now that is a hell of a deal. At $4.00 per quart, it's going to get me to switch from Rotella-T, currently at $3.38 per quart.

Might even consider running it up to 7.5K instead of the 5K that the Rotella-T goes.

[pawoSD]

Is it normal for oil to register lower than it did before your oil change? Last weekend I changed the oil in mine from Delvac 1300 Super to Shell Rotella T and now the gauge generaly sits at about 1.8 to 1.9 bar instead of the 2.0 it used to be at at idle. However, sometimes its at 2, most of the time at 1.8......I've never changed the o-rings, are those the little things at the end of the rod from the oil filter housing cover? Are those rubber?! I was picking at them a little and I could swear they were hard enough to be metal......if those are rubber then they're in for a change next time around. They certainly felt like metal washers though.

[Brian Carlton]

Originally Posted by pawoSD

Are those rubber?! I was picking at them a little and I could swear they were hard enough to be metal......if those are rubber then they're in for a change next time around. They certainly felt like metal washers though.

They are standard rubber o-rings. And yours are probably on there since the vehicle was made.

When you go to remove them, they will shatter like a piece of plastic.

[Palangi]

When those rubber o-rings feel like metal, they needed changing 5 years ago. Mine were petrified when I got both cars. You will be amazed at how the crumble as you chisel them off. It won't make any difference in idle oil pressure though.

[Dervman]

Originally Posted by billrei

Is this reading at idle or at speed? My oil guage pegs itself high at anything much above an idle so I would never notice the difference at speed. If you see a difference at speed I would be worried about your oil pressure.

I noticed the higher oil pressure at both idle and high speed with the engine at normal operating temperature. My gauge pegs when the oil is cold and drops just below that when hot and never moves at anything above 1000rpm. It is still well into the "3" at the top of the gauge but the needle now sits just a bit higher since the oil change, At idle it would fall a fraction below the "2" but now sits on the "2" mark. I think my oil pressure is just fine.

I think Brian may be right about the slight difference between old and new oil, although I have never noticed it before and the "old" oil was only in there for 5k miles.

As far as viscosity range is concerned I doubt there is any validity to that, at least with true synthetics. When Mobil-1 was first introduced it was sold as a 0W-50 and met all testing requirements for that range. The story I heard (from an Exxon retiree) was that the auto shops and retail outlets complained because nobody would bother changing their oil from summer to winter and they would lose some business, so Mobil repackaged it with conventional viscosity ranges.

[Gurkha]

Why not give Delo Synthetic a try, I am a regular Delvac user as well as Delo and I have noticed that the Delo fares better on the pressure front than Delvac but the difference isnt much.

[michakaveli]

Originally Posted by Secret Squirrel

If you want a heck of a deal $ wise look for the newly arriving 5 quart jugs of the M1 Truck & SUV that Walmarts are rolling out this week. Right under $20 for a 5 quart jug.

That will be NICE!!!

[Dana B.]

Originally Posted by Gurkha

Why not give Delo Synthetic a try, I am a regular Delvac user as well as Delo and I have noticed that the Delo fares better on the pressure front than Delvac but the difference isnt much.

Impossible to find.

[billrei]

Originally Posted by Dervman

When Mobil-1 was first introduced it was sold as a 0W-50 and met all testing requirements for that range. The story I heard (from an Exxon retiree) was that the auto shops and retail outlets complained because nobody would bother changing their oil from summer to winter and they would lose some business, so Mobil repackaged it with conventional viscosity ranges.

Being old enough to remember when Mobil 1 was first introduced to the market in the late 1970's it came out with a very low viscosity something like 5W-20. The main problem was Detroit Iron of that era would piss this oil out through the seals like crazy forcing Mobil to eventually raise the viscosity. Sometime in the early 80's Mobil dropped the claim to 25,000 mile oil change intervals.

[Palangi]

Yep, the original Mobil1 was 5w20. It came in metal cans. Detroit V8's would eat that stuff as fast as you could pour it in there.