M1 0W-40/15W-50 mix, 12 mo/20k miles, '90 Saab 900

[Eiron]

Code:
Vehicle 1990 Saab 900, 2.0L 16v I4 (N/A)

Miles on engine 220,074

Oil type Mobil 1, 0W-40 & 15W-50

Miles on oil 19,895

Time on oil 12 months (04.Nov.06 – 03.Nov.07)

Oil capacity 4 qts

Oil added 4.1 qts

Oil filter AC Delco PF13, UK manufacture, not changed during OCI

Air filter K&N drop-in, last cleaned at 150,000 miles

Driving Use 40% city, 60% hwy (by distance); 60% city, 40% hwy (by time)

Sampling method Vacuum pump via dipstick fill tube

-

Copper 7

Iron 12

Chromium 1

Aluminum 3

Lead 4

Tin 0

Molybdenum 67

Silicon 0

Sodium 5

Potassium 1

Calcium 2561

Magnesium 21

Zinc 1172

Boron 125

Phosphorus 1000

Water Neg

Glycol Neg

Viscosity 18.43

-

Lab S.O.S. Fluid Analysis, H.O. Penn Machinery


Previous 20k mile M1 0W-40 UOA

I guess the oddest thing about this run was my combination of oil. I started out with a 50/50 mix (2 qts ea) of M1 0W-40 & M1 15W-50 EP. At first I alternated, adding a bit of 0W-40, then a bit of 15W-50, then going back to 0W-40, etc. I did that for the first two additional qts. After that, the weather was warm enough to top up just with 15W-50. Obviously, with my higher average speeds due to more hwy miles, my oil consumption went up a bit compared to my previous 20k run of 0W-40. The last OCI averaged about 1 qt every 7k miles. This run was about 1 qt every 5k miles. I knew this run was going to complete in about a year, so I didn’t bother changing the oil filter. The current run will be exactly the same oil combo, but using the Purolator PureOne PL10017 filter instead.

The NGK copper plugs were installed prior to this OCI at 197k & not changed until after the end of the run. At 210k I ran a can of BG 44K thru the tank, then changed out the huge (12oz?) fuel filter. The coolant was replaced at 218k since it was 3yrs/45k mi old. All other repairs were unrelated to any engine oil abuse.

Enjoy!

 

[TR3-2001SE]

Great report. Did you use the Mobil 1 EP 15w-50 or the regular mobil 1 15w-50?

 

[buster]

Quote:
Oil capacity 4 qts
Oil added 4.1 qts


Looks good. Lot of make up oil. You basically end up with a full change.

 

[glennc]

Still good though. Statistically I suppose 1/4 of the oil has gone 15-20k miles, 1/4 has gone 10-15k, and so on. So the average molecule has been in there 10k or something like that.

Also I might point out that this appears to be an example of a K&N filter that has worked very well. I don't know how you can have NO Si but it does appear that the filter is keeping the dirt out very well. I'd be interested to see the results just after cleaning/oiling, for comparison.

Obviously a happily-wearing engine.

 

[JAG]

Originally Posted By: glennc
Still good though. Statistically I suppose 1/4 of the oil has gone 15-20k miles, 1/4 has gone 10-15k, and so on. So the average molecule has been in there 10k or something like that.

That's an interesting question to answer. I did some number crunching that shows the trends of what happens when topping up on oil. The scenario I used doesn't match this guy's scenario but still gives an idea of the situation.

I assumed that at 5K, 10K, 15K, and 20K miles, 1/4 of the sump volume is replaced with new oil. Yeah it's dumb that I have 1/4 of the sump being replaced and then no more miles are racked up but oh well.

At 20K miles:
- 31.6% of the oil molecules have been in sump for 20K miles
- 10.6% of original oil molecules has been in sump for 15K miles
- 14.1% of original oil molecules has been in sump for 10K miles
- 18.8% of original oil molecules has been in sump for 5K miles
- 25% of original oil molecules has been in sump for 0K miles

 

[glennc]

I get exactly the same numbers when I look at it in more detail as well, though in this case the result is not that different from the first-guess estimate: it results in a weighted average mileage of 10,260 miles for the oil. In the real world probably a bit more since, as you say, you would be adding each quart a little sooner than what you've modeled.

I always sort of wondered about that as well.

 

[JAG]

Good, then I must have done it correctly. Thanks for the reply.

 

[Eiron]

I forgot to mention that I ran an Auto-Rx clean (3k mi, Delvac 1300 Super 15W-40) & rinse (3k mi, Castrol Syntec Blend 10W-40) between my last 20,000 mile run of M1 0W-40 & this 20,000 mile run of mixed M1 oil.

TR3 2001SE, I'm using EP, but it's the non-API-certified stuff that Target was clearancing about 2 yrs ago.

buster, yeah, the higher driving speeds & slow (but constant) drip combine to lose 1 qt every 5k miles. Not too bad for an abused 18 yr old engine with 220k miles on it, but not as good as when my driving is kept below highway speeds. For around town driving my burn & drip loss is about 1 qt every 10k miles.

glennc, this K&N now has nearly 80k miles on it since it was last cleaned. As you might imagine, it's pretty well coated with debris. Since K&N recommends going no longer than 100k miles between cleanings, I'll probably clean it at the end of this OCI or in the middle of my next one.

glennc & JAG, if you'd really like a challenge, figger the degradation the way the oil was added:
Approximately every 600 miles I'd add 4 oz of oil. By the time I got to the end of this 20,000 mile interval, it was down by 4 oz. Obviously, since I was changing it, I didn't bother topping up that last time.

For extra credit, you can figger the vis rates:
I started with 2 qts 0W-40 & 2 qts 15W-50, & topped up starting with 15W-50. I then alternated between 0W-40 & 15W-50, 4 oz at a time, until I finished those two qts. The last 2.1 qts were all 15W-50.

 

[JAG]

Eiron, I'm tempted to tackle those questions but I'm sorry to say that mind already has enough technical questions to tackle already (it gets numb if overworked) . Maybe some day soon but not now. If you want to try the first question, Excel would be the way to do it given the large number of data points.

 

[Al]

0 silicon..uhhhh....no. Maybe the 6th tuesday of the month. But not today.

 

[Eiron]

Originally Posted By: Al
0 silicon..uhhhh....no. Maybe the 6th tuesday of the month. But not today.

LOL, glad you enjoyed the report! And thanks for the infinitely constructive comments. It's always good to know we can count on you for support.

But, what I hear you saying is, "I can't believe my eyes! I must know more! I must seek clarification directly from the source of this font of knowledge!"

Well, fear not my friend, for salvation is at hand. I present to you the Path To Enlightenment! Seek within! Your guides on this quest shall be: Denis, Defender of Sales, and Heather, Queen of The Lab. Divine communication can be directly achieved by the numerical sequence of (860) 594-4800. Go forth, ye student of knowledge, and truth shall ye find!

 

[OMCWankel]

Excelent report Eiron!

M1 15W-50 is still a very robust oil, that works well straight and as an additive. I did a mix with M1 10W-30 and M1 15W-50 in a Miata that gave good results.

 

[Eiron]

Thanks OMCWankel! I agree WRT M1 15W-50, & I'm surprised to hear from someone using it in a Miata. I generally think of Asian cars fairing better on thinner viscosities than their Euro counterparts. What motivated you to try your mix? How was it different compared to using only 10W-30 in the Miata? Have you tried 0W-40 in it? I'd think that would be an excellent oil to run in that car in your location.

 

[OMCWankel]

The first generation Miata's had undersized cooling systems. This has been fixed in the third generation Miata. The thicker oil is to maintain oil pressure on hot (90 F +) days with the AC on. I am now experimenting with 10W oils in my '97 and will do a UOA soon. The 10W-40 oil I am currently using is maintaining oil pressure on hot days. I am thinking of the next step, probably a 5W-40 HDEO.

 

[Donald]

I think the lab had an error in the SI. Just no way it would be zero. Even if it was a new Amsoil Ea air filter which is probably the best out there these days I would not suspect zero.

If I got back a lab test with something like that, I would immediately ask for a retest while they still had the sample available.

 

[Shannow]

Originally Posted By: Eiron
glennc & JAG, if you'd really like a challenge, figger the degradation the way the oil was added:
Approximately every 600 miles I'd add 4 oz of oil. By the time I got to the end of this 20,000 mile interval, it was down by 4 oz. Obviously, since I was changing it, I didn't bother topping up that last time.


Went to 19,800 miles, and 4 Oz down at 19,800.

44.89 ounces have done 19800
1.45 ounces have done 19200
1.49 ounces have done 18600
1.54 ounces have done 18000
1.59 ounces have done 17400
1.64 ounces have done 16800
1.7 ounces have done 16200
1.75 ounces have done 15600
1.81 ounces have done 15000
1.87 ounces have done 14400
1.93 ounces have done 13800
1.99 ounces have done 13200
2.05 ounces have done 12600
2.12 ounces have done 12000
2.19 ounces have done 11400
2.26 ounces have done 10800
2.33 ounces have done 10200
2.41 ounces have done 9600
2.48 ounces have done 9000
2.56 ounces have done 8400
2.65 ounces have done 7800
2.73 ounces have done 7200
2.82 ounces have done 6600
2.91 ounces have done 6000
3.01 ounces have done 5400
3.1 ounces have done 4800
3.2 ounces have done 4200
3.31 ounces have done 3600
3.41 ounces have done 3000
3.52 ounces have done 2400
3.64 ounces have done 1800
3.75 ounces have done 1200
3.88 ounces have done 600

 

[JAG]

Kudos to Shannow!

 

[Shannow]

Hardest part was finding out how many ounces are in a quart...hasn't been taught down here in my lifetime.

 

[DmanWho]

Could the older and possibly Silicone laden oil, be leaking out and/or getting consumed, at a faster rate than the make-up oil?

 

[REDDOG]

Eiron,

Excellent report! Yes, the volume of the crankcase was matched by make up oil, but you went 20k (and 1 year) on just over 8 qts of oil. If this were a 10k run with 2 qts make up oil, I'd still think it was impressive for 220k on the clock. This engine looks like it has many of these 20k runs left in it. Thanks for posting this very interesting report.

REDDOG