MMO Studies RTS 5w40 in 2003 Deville Northstar

[ronrackley]

I think this winds up my studies of MMO that started when I noticed such outstanding wear numbers on the first OCI run I had checked with it. RTS in gas means 8 ounces at each fill up, and the fill ups average about 16 gallons - giving slightly higher than the 4 ounces per 10 gallon concentration recommended on the label.

It seems that the wear numbers were slightly better with MMO in the oil, but the TBN dropped faster. It seems that the TBN dropped a little faster with just MMO in the gas, too. I can't tell any difference in the oil usage with or without MMO.

I'm through experimenting with MMO in the oil. Despite what appear to be very minor differences, the wear numbers look excellent with just the Rotella T synthetic in the sump. I will probably still use 20% MMO in the oil for an OCI next time I buy a used car just to be sure it is clean inside - which is the way this saga started. I will continue to use it regularly in my gas.

Note: The 5000 miles in the comments for the last run is an approximate number. I left the oil in after the previous sample, added 1 quart of MMO after another 1000 miles or so, and then took another sample at the indicated mileage of the last test.

 

[demarpaint]

Nice report Ron, thanks for sharing.

 

[scurvy]

Originally Posted By: ronrackley
I think this winds up my studies of MMO that started when I noticed such outstanding wear numbers on the first OCI run I had checked with it. RTS in gas means 8 ounces at each fill up...


I think you mean MMO in the gas; Shell Rotella T6 5w40 in the crankcase.

The Spicer lubricity study showed that waste motor oil doesn't offer much lubricity enhancement!

 

[willix]

40w is a bit heavy for a Northstar IMO.

 

[SZR48207]

Originally Posted By: willix
40w is a bit heavy for a Northstar IMO.


This is also my thought. Doesn't Rotella typically run heavy?

 

[Panzerman]

5w40 would cut back oil consumption in the Northstar, which looks like what it did. I would not think it is too heavy. How come everyone looks at the big number, then the little number?????

 

[ronrackley]

Originally Posted By: scurvy
Originally Posted By: ronrackley
I think this winds up my studies of MMO that started when I noticed such outstanding wear numbers on the first OCI run I had checked with it. RTS in gas means 8 ounces at each fill up...


I think you mean MMO in the gas; Shell Rotella T6 5w40 in the crankcase.

The Spicer lubricity study showed that waste motor oil doesn't offer much lubricity enhancement!


Thank you. You are correct. Sorry.

 

[ronrackley]

Originally Posted By: willix
40w is a bit heavy for a Northstar IMO.


It is one weight heavier than recommended in the high number (40 instead of 30) so yes, it is thicker. That seems to be perfectly OK in my engines.

I have used RTS 5w40 for several years in my cars with excellent UOAs when I've run them and the gas mileage has been basically the same as when I ran 5w30 and 10w30 oils - maybe a couple of tenths of a mile per gallon less, at most, as explained in other posts I've made here about that.

I do not believe the 40 weight to be necessary or even better for my engines. It's not about that, it's about the additive package as far as I'm concerned.

I only went to RTS 5w40 when they reformulated the 5w30 and 10w30 oils I had been using for years [Mobil 1] to reduce their ZDDP additive level a few years ago. I just wanted to keep the same basic additive package that oils had when my engines were originally designed "for good measure," I guess you could say, and the HDEOs gave me that. I could only find HDEO in 5w40 and 15w40 on store shelves, so that's what I started to use.

I'm thinking about giving the new Rotella T5 10w30 blend a try when my stock of RTS runs out, which will be later this year. It will give me an HDEO additive package in the recommended weight. When I do, I'll be watching consumption closely and I'll run another UOA.

 

[demarpaint]

There are also people who go up a grade in viscosity and add a qt of MMO "thinning" the oil. From your report you have nothing to worry about. I plan on giving M1 5W40 TDT a try unaltered in my 93 Aerostar to see if it slows a leak any and reduces oil use. 5W20 was actually better than 5W30 until the leak got worse. Now I'm going to head in the opposite direction this time.

 

[ltslimjim]

Adjusting one grade, especially relative to the season, is perfectly fine. Just don't go thicker in the winter, and thinner in the summer; to play it safe at first if you haven't used oil out of the recommended grade before. T5 10w30 would be an interesting oil analysis to compared here. It is the HDEO version or just the synthetic blend T5?

.02 cents...

 

[ronrackley]

Originally Posted By: ltslimjim
Adjusting one grade, especially relative to the season, is perfectly fine. Just don't go thicker in the winter, and thinner in the summer; to play it safe at first if you haven't used oil out of the recommended grade before. T5 10w30 would be an interesting oil analysis to compared here. It is the HDEO version or just the synthetic blend T5?

.02 cents...


T5 is their synthetic blend and I believe it is also an HDEO insofar as the additives are concerned.

 

[ltslimjim]

Originally Posted By: ronrackley
Originally Posted By: ltslimjim
Adjusting one grade, especially relative to the season, is perfectly fine. Just don't go thicker in the winter, and thinner in the summer; to play it safe at first if you haven't used oil out of the recommended grade before. T5 10w30 would be an interesting oil analysis to compared here. It is the HDEO version or just the synthetic blend T5?

.02 cents...


T5 is their synthetic blend and I believe it is also an HDEO insofar as the additives are concerned.


I vaguely remember seeing T5 in a white bottle 10w30, and a silver bottled 10w30 HDEO oil.

 

[Hokiefyd]

Shortly before I sold my '97 Cadillac to my brother, who lives in Arizona, I put in some 15w40 (10W-30 spec'd). With 160,000 miles on the engine, I figured it couldn't hurt, and might stand up to the 110*F heat he has down there. Wouldn't you know it, that Northstar seemed to REALLY like that slightly thicker oil. With tolerances loosened up a little bit after 100,000 miles and more, going up a grade won't hurt anything. Besides, this engine was designed in the late '80s, and tends to prefer thicker oils to thinner ones.

 

[ronrackley]

Originally Posted By: ltslimjim

I vaguely remember seeing T5 in a white bottle 10w30, and a silver bottled 10w30 HDEO oil.


From the Shell website, referring to Rotella T5, it meets:

"...some of the most stringent heavy duty engine oil specifications globally, such as API CJ-4, ACEA E9, and Volvo VDS-4."

It is therefore an HDEO. It also meets the SM requirements for gasoline engines, so it is a fleet oil.

I expect it is an excellent HDEO synthetic blend that comes in 10w30 at low cost. I'm going to try it.

 

[Hokiefyd]

I ran T5 in my former Dakota and it ran just fine. The older Rotella 10w30 seemed to make it feel sluggish, but I didn't notice that with the newer T5.