M1 0w40; 4710 mi; 1991 Lotus Elan Turbo; 51,630 mi

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Here's the new analysis of the Mobil 1 0w40

UOA_121106.png


1. The mileage was almost the same for the two oil runs (4660 and 4710 mi). The owners manual says to replace at 6000 mi.
2. The first run used Castrol Syntec 10W30. The second used Mobil 1 0w40. The car now has Mobil 1 0w40.
3. The first run used a WIX 51334 filter with a Beta ratio of 95% at 20 microns. The second used a K&N HP-1004 filter with a Beta ratio of 93% at 20 microns. The car now has a PureONE PL14459 filter with a Beta ratio of 99.9% at 20 microns.
4. The first run consisted of a lot of highway driving. The second had more city driving, short trips, and an autocross.

The largest issue in this report is the fuel, up to 2.0% from 0.8% The cause of this is likely due to driving style, short trips and idling. The car did a short trip from cold immediately before the oil change.
When the car was purchased 10,000 miles ago a dry compression test was done: 140, 135, 130, 140 psi on cylinders 1-4.

Mobil 1 0w40 starts off with a viscosity of 13.5 cSt at 100 degC, and because of the fuel and shearing effects it thinned to 10.56 cSt. If the fuel had stayed out of the oil the viscosity would have been higher, resulting in better engine protection. However, the Mobil 1 even with the fuel dilution was thicker than the Castrol 10w30 at the end of the run.

Mobil 1 0w40 starts off with a flashpoint of 446 degf, the fuel dilution reduced this to 335 degf.

TBN was robust, showing a lot of un-reacted additives still remaining in the Mobil 1, however because of the lowering of the viscosity due to the fuel I think it was time to replace the oil.

Comparing formulations between the Castrol Syntec and the Mobil 1 we see that:
Syntec has a little more molybdenum, an anti-wear additive
Mobil 1 has 3x more boron, a corrosion inhibiter, anti-wear and anti-oxidant additive
Mobil 1 has 1.5x more calcium, a detergent and dispersant additive
Syntec has 4.5x more magnesium, a detergent and dispersant additive
Mobil 1 has a little more phosporus and zinc, anti-wear, anti-oxidant additives

Thread cross-references:
LEC
BITOG Run 1
 
Perhaps CATERHAM or someone else can answer this:

I am thinking about purchasing a case of the Mobil 1 0w50 racing oil and blending it for 2 reasons.
I see that it has significantly more ZDDP than the 0w40 (1750/1850 vs 1000/1100)
I see that is has a thicker operating viscosity (17.2 cSt vs 13.5 cSt)

The engine has a 4qt capacity, and my first shot in the dark would be 1qt 0w50 and 3qt 0w40.

My objective in doing this would be to lower the amount of Iron showing up in the UOA.

The car does have an analog oil pressure gauge. Starting up from cold with the 0w40 it hovers around 5 to 7 bar depending on air temp. Once at steady state and idling it hovers around 2.5 bar. During moderate to heavy throttle it hovers around 5 bar.

The owners manual provides a lot of options of synthetic grades, 10w30 (summer), 5w30 (winter), but also lists 15w40 and 5w50. The last service bulletin (1996) for the car added Mobil 1 0w40.

The car is only driven in the summer, went into hibernation right after the oil change.

here is a pic:
189158_10101893092713958_457095746_n.jpg
 
You haven't defined what the length of your short trips are but in my experience it's not getting the oil up to temperature every time the engine is started that is the main cause of fuel dilution, not idling so much.
I presume you don't have an oil temperature or even a calibrated coolant temp' gauge? How hot does your engine get?
 
You need to drive around for at least half an hour before sampling the oil, otherwise the fuel figure might be in error. Interesting how little difference the oil brand made, although they are different viscosity ranges, so it would be more interesting to see M1 0/40 compared with Castrol Edge 5/40.
 
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First your UOA is not bad at all.

No forget M1 R 0W-50, it's actually not any heavier than M1 0W-40 with the same HTHSV of 3.8cP, assuming their PDS info is correct although it was previously listed at 4.1cP.
I can't see any reason to deviate from M1 0W-40, the 900-1000 ppm of phosphorous is fine for your engine.
Based on your oil pressure, your oil is more than heavy enough.

About the only advise that I can give is if you can, every time you start the engine make sure the oil gets hot enough for the OP to drop to 2.5 bar.
 
The short trips are about 5 miles of city driving (to and from work), I can tell the oil isn't getting to temp indirectly through the oil pressure gauge at idle.

The thermostat opens at 180 degf, the cooling fans come on at 210 degf and turn off at 200 degf. When the car is being driven there is enough airflow over the radiator to maintain the coolant below 210 degf.

I have software that interfaces with the computer, back in May I did a log, and during the run once the engine reached its operating temp the manifold air temp was at 32 degC and coolant temp was 80 degC
 
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Wow. Those are really high oil pressures. I don't know that you would want to go thicker by adding a quart of 0w-50. Perhaps a quart of thinner oil would help the iron. The oil would circulate faster and achieve temp faster,perhaps negating some iron.
Not sure that it would make a huge difference though.
 
Okay I just wanted to make sure you coolant T'Stat at least was operating correctly.
Yes 5 miles is a short trip and as you know your oil isn't getting up to temp' by the OP. So yes that's the problem and I don't know what you can do short of finding a reason to run some errands on the way home.

BTW, your optimum OP is likely closer to 2 bar on idle. Do you recall what your OP was like with the Castrol 10W-30?
I'm inclined to suggest an oil like Red line 0W-30 if you don't mind the cost. It's ester based with a boat load of moly and Phos'.
 
I do not recall what the OP at idle was with the Castrol 10W30.
The car has the analog gauge shown below:
gauges.jpg


I am assuming the unmarked line is 2.5 bar, however I am not 100% sure. I am also assuming the mark is here showing the proper idle OP, same with the mark at 5 bar at throttle OP. The ALDL interface does not see oil pressure.

I have 2 other cars, SAAB 9-3 2.0t and SAAB 9-3 Aero, both of these require M1 0w40 and I get very good UOAs using it. I'd like to stay with the M1 0w40 across all 3 just to keep inventory simple.

Next summer I'll take a sample after 5k miles, try to lengthen the trips to evaporate out the oil, and see where we are.
 
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Originally Posted By: CATERHAM
First your UOA is not bad at all.

No forget M1 R 0W-50, it's actually not any heavier than M1 0W-40 with the same HTHSV of 3.8cP, assuming their PDS info is correct although it was previously listed at 4.1cP.
I can't see any reason to deviate from M1 0W-40, the 900-1000 ppm of phosphorous is fine for your engine.
Based on your oil pressure, your oil is more than heavy enough.

About the only advise that I can give is if you can, every time you start the engine make sure the oil gets hot enough for the OP to drop to 2.5 bar.


Is 900 ppm phosphorous really OK for this engine?
I have been doing some research:
The Lotus manual specs a SF or SG oil
oil_spec_manual.png

I know that this was the latest spec at the time, but I think SG was the last spec before phosphorus and zinc started to be limited.
I have also read that ZDDP is very good at preventing wear in 'flat tappet' engines.
This car has flat hydraulic valve lifters (no rollers) and a dual overhead cam.

Is ZDDP only beneficial for overhead valve (aka pushrod) engines, or would it also help in my overhead cam engine?

My thought was to bring the ZDDP levels in the oil to what the Mobil 1 15w50 is by mixing either Racing 0w30 or Racing 0w50 with the 0w40. I was more inclined to use the 0w50 because it wouldn't reduce the HTHS numbers.

If it helps, here are the valve and camshaft specs I have on the engine:
valve_specs.png
 
Originally Posted By: CATERHAM
First your UOA is not bad at all.

I can't see any reason to deviate from M1 0W-40, the 900-1000 ppm of phosphorous is fine for your engine.
Based on your oil pressure, your oil is more than heavy enough.

About the only advise that I can give is if you can, every time you start the engine make sure the oil gets hot enough for the OP to drop to 2.5 bar.


this! ^^^

The hardest duty there is is short tripping the car at less than optimal temp.

Better be careful when it's cold as the oil pressure is actually a bit high, not a problem as long as you keep the revs and boost down. But you need some WORK for this motor to help with the fuel dilution.

Hot oil is happy oil!
 
Originally Posted By: ccb056
Originally Posted By: CATERHAM
First your UOA is not bad at all.

No forget M1 R 0W-50, it's actually not any heavier than M1 0W-40 with the same HTHSV of 3.8cP, assuming their PDS info is correct although it was previously listed at 4.1cP.
I can't see any reason to deviate from M1 0W-40, the 900-1000 ppm of phosphorous is fine for your engine.
Based on your oil pressure, your oil is more than heavy enough.

About the only advise that I can give is if you can, every time you start the engine make sure the oil gets hot enough for the OP to drop to 2.5 bar.


Is 900 ppm phosphorous really OK for this engine?
I have been doing some research:
The Lotus manual specs a SF or SG oil
oil_spec_manual.png

I know that this was the latest spec at the time, but I think SG was the last spec before phosphorus and zinc started to be limited.
I have also read that ZDDP is very good at preventing wear in 'flat tappet' engines.
This car has flat hydraulic valve lifters (no rollers) and a dual overhead cam.

Is ZDDP only beneficial for overhead valve (aka pushrod) engines, or would it also help in my overhead cam engine?

My thought was to bring the ZDDP levels in the oil to what the Mobil 1 15w50 is by mixing either Racing 0w30 or Racing 0w50 with the 0w40. I was more inclined to use the 0w50 because it wouldn't reduce the HTHS numbers.

If it helps, here are the valve and camshaft specs I have on the engine:
valve_specs.png



Yes, it is more than adequate for your application. My M5 has the same setup, as do the new Ford DI engines (cam over bucket), and the old Zetec. You'll be fine.
 
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