Post Your Used Oil Analysis (UOA) Thread
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Post Your Used Oil Analysis (UOA) Thread
If any engine in the world requires routine oil analysis, it's a turbocharged rotary, yet you rarely see them posted here (interestingly, the S2KI guys post them all the time).
Fuel dilution averages >5% in as little as 1,000 miles with these cars. The oil often loses at least one, if not two, viscosity grades (i.e. your 20w-50 "racing oil" quickly degrades to a 10w-30). Sobering statistics. Some claim that careful side seal clearancing reduces fuel dilution, but haven't offered proof. Now's your chance.
I'll be posting my recent analysis of Amsoil 20w-50 (Blackstone Labs) shortly. Sure enough, 5% fuel dilution and viscosity dropped to the equivalent of 10w-30 grade.
Fuel dilution averages >5% in as little as 1,000 miles with these cars. The oil often loses at least one, if not two, viscosity grades (i.e. your 20w-50 "racing oil" quickly degrades to a 10w-30). Sobering statistics. Some claim that careful side seal clearancing reduces fuel dilution, but haven't offered proof. Now's your chance.
I'll be posting my recent analysis of Amsoil 20w-50 (Blackstone Labs) shortly. Sure enough, 5% fuel dilution and viscosity dropped to the equivalent of 10w-30 grade.
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Get it analyzed. It's cheap and an interesting assessment of engine wear. High Pb and Cu in my engine has me a bit worried, but it might also be the turbos. I'll probably switch to dino juice and change it more frequently.
Scary how fast the viscosity drops with high fuel dilution.
Scary how fast the viscosity drops with high fuel dilution.
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Hard to believe with all the members here I've only seen one other person post a UOA. It's a cheap diagnostic, like checking your blood.
You can also get a UOA on your trans and diff fluid btw, which are equally interesting.
You can also get a UOA on your trans and diff fluid btw, which are equally interesting.
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since we like to use big oil coolers, are we over-cooling the oil such that it never reaches a high enough temp to evaporate fuel and we end up with high % fuel in the oil?
I have twin 19-row mocals with thermostat and the oil temp at the oil pan hovers about 160-180 F most of the time. It will only increase in heavy traffic on a hot day or during mountain runs and the hottest i've seen it is about 230F.
some bypass oil filter systems have a heater to bring the oil to a high temp to evaporate moisture and fuel, in theory you never need to change the oil with these systems as long as you change the filter and top off the used oil at the recommended intervals. maybe we need something like this?
I have twin 19-row mocals with thermostat and the oil temp at the oil pan hovers about 160-180 F most of the time. It will only increase in heavy traffic on a hot day or during mountain runs and the hottest i've seen it is about 230F.
some bypass oil filter systems have a heater to bring the oil to a high temp to evaporate moisture and fuel, in theory you never need to change the oil with these systems as long as you change the filter and top off the used oil at the recommended intervals. maybe we need something like this?
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The problem is two fold: FDs are generally tuned pig rich, some people are seeing 10s AFRs. That's a shitload of gas, whihc finds it's way past the seals into the oil under boost. Second, these engines don't seal as well as a four stroke piston engine to begin with, and even many piston engines have fuel dilution issues (see the "GreenHulk" forum, you'd be shocked how many supercharged waverrunners are seeing 5% fuel dilution). It seems to be inherent to boosted engines, espeically at AFRs < 12, and even more prevalent in rotaries. Unfortunately, I'm not sure there is a "fix" other than changing the oil religiously every 1500-2000 miles. I plan to get my next UOA at 1,000 miles just to see how fast it gets to 5%.
some bypass oil filter systems have a heater to bring the oil to a high temp to evaporate moisture and fuel, in theory you never need to change the oil with these systems as long as you change the filter and top off the used oil at the recommended intervals. maybe we need something like this?
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Latest UOA - Only 1,000 Miles
Notice how much this 10w-40 Castrol thinned out-of-spec with only 1,000 miles....8% fuel dilution already (!)
good ol FDs....."The Fix" won't fix this problem, unfortunately
good ol FDs....."The Fix" won't fix this problem, unfortunately
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For my next interval I'm going to try Shell Rotella T 15w-40 "heavy duty" (rated for diesel and gas engines). It's gotten good reviews on BITOG and it's cheap. I'm hoping the viscosity will hold up a little better with the fuel dilution. No more synthetics for me in this engine...waste of money.
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I've got a new Blackstone report to post but was hoping some other members would post a report as well. I'm still seeing excessive copper and lead in the 20-50 ppm range, indicating excessive bearing wear. Oil sheared down to a 5w-20 range in just 2,000 miles (15w-40 Shell Rotella T), with about 6% fuel dilution. These engines are brutal on oil. Maybe I'll try Amsoil Racing 60 weight to try to save my bearings.
Last edited by no_more_rice; 06-18-10 at 04:25 PM.
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Interesting read. I just did an oil change after 2500KM and it was black as tar. I thought I had a fuel leak when I was under the car because the gas smelled so strong. It wasn't till I was pouring the dirty oil back in the container did I figure out where the smell was coming from.
In another thread started by howard, he mentioned he uses mobile 1 5-30 ( I think ). If you are starting off with 10 and dropping to 5 where would the 5 be after 2500km? Or am I misunderstanding how it dilutes?
In another thread started by howard, he mentioned he uses mobile 1 5-30 ( I think ). If you are starting off with 10 and dropping to 5 where would the 5 be after 2500km? Or am I misunderstanding how it dilutes?
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The first oil change in post #2 was for (full synthetic) Amsoil 20w-50. Even that doesn't seem to be able to stand up to the abuse of a turbo rotary, which is why I'm thinking I need to go to a straight weight racing oil.
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I think I'm going to try this, or something very similar
http://www.amsoil.com/storefront/ahr.aspx
http://www.amsoil.com/storefront/ahr.aspx
AMSOIL Synthetic Super Heavy Weight Racing Oil (AHR) is a high-viscosity oil designed for high-horsepower racing engines, typically supercharged and alcohol-burning or nitro-fueled, requiring a high-viscosity oil to resist the thinning effects of fuel dilution.
AMSOIL Synthetic Super Heavy Weight Racing Oil is formulated specifically for wear protection and friction reduction in the extreme conditions of racing. It is race proven and reduces friction, promotes power and inhibits wear.
AMSOIL Synthetic Super Heavy Weight Racing Oil is formulated specifically for wear protection and friction reduction in the extreme conditions of racing. It is race proven and reduces friction, promotes power and inhibits wear.
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Great read on why the march toward thinner and thinner oils is often mis-guided, especially for high load conditions
http://www.machinerylubrication.com/Read/518/motor-oils
http://www.machinerylubrication.com/Read/518/motor-oils
The auto manufacturers now recommend thinner oils for their vehicles than in the past. Years ago, SAE 10W-40 was the most commonly recommended viscosity grade, later migrating to SAE 10W-30. SAE 5W-30 is most popular now, but Ford and Honda recommend SAE 5W-20. It is likely that more widespread adoption of SAE 5W-20 and other thin oils may occur to help comply with CAFE requirements.
Because of the change in cold-flow requirements and the fuel economy test pushing formulators toward the bottom of the viscosity grade, today’s SAE 10W-30 oils are more like yesterday’s (GF-1 spec) SAE 5W-30 oils. On top of that, there is a trend toward auto manufacturers recommending thinner grades. This seems ridiculous. SUVs and trucks, with their inherently less-efficient four-wheel drive and brick-wall aerodynamics, need powerful, gas-guzzling engines to move their mass around in a hurry. In response, auto manufacturers recommend using thin oils to save fuel. Incredible!
Thinner oils have less drag, and therefore less friction and wear. Right? Perhaps in the test engine or engines that experience normal operation. But somewhat thicker oils may offer more protection for more severe operations such as driving through mountains, pulling a boat, dusty conditions, short trips, high rpm, overloading, overheating and overcooling.
Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.
Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.
Because of the change in cold-flow requirements and the fuel economy test pushing formulators toward the bottom of the viscosity grade, today’s SAE 10W-30 oils are more like yesterday’s (GF-1 spec) SAE 5W-30 oils. On top of that, there is a trend toward auto manufacturers recommending thinner grades. This seems ridiculous. SUVs and trucks, with their inherently less-efficient four-wheel drive and brick-wall aerodynamics, need powerful, gas-guzzling engines to move their mass around in a hurry. In response, auto manufacturers recommend using thin oils to save fuel. Incredible!
Thinner oils have less drag, and therefore less friction and wear. Right? Perhaps in the test engine or engines that experience normal operation. But somewhat thicker oils may offer more protection for more severe operations such as driving through mountains, pulling a boat, dusty conditions, short trips, high rpm, overloading, overheating and overcooling.
Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.
Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.
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Very interesting stuff. I am new to rotaries, and it is one of the most hostile environments for oil, that I have heard of.
Anyone using a Trasko-Bee (now "Trasko USA"?) filter? The ones developed for the contract for the Tokyo govt., for increased engine life?
Anyone using a Trasko-Bee (now "Trasko USA"?) filter? The ones developed for the contract for the Tokyo govt., for increased engine life?
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A different oil filter won't do anything for fuel dilution, which is what thins the oil so rapidly. I just dumped some Shell Rotella 15w-40 that had been in the car for only ~200 miles and it was already dark brown and smelled like gas....incredible. You can understand why so many people say screw it and go buy a Cayman S, these cars are a constant battle.
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
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A different oil filter won't do anything for fuel dilution, which is what thins the oil so rapidly. I just dumped some Shell Rotella 15w-40 that had been in the car for only ~200 miles and it was already dark brown and smelled like gas....incredible. You can understand why so many people say screw it and go buy a Cayman S, these cars are a constant battle.
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
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A different oil filter won't do anything for fuel dilution, which is what thins the oil so rapidly. I just dumped some Shell Rotella 15w-40 that had been in the car for only ~200 miles and it was already dark brown and smelled like gas....incredible. You can understand why so many people say screw it and go buy a Cayman S, these cars are a constant battle.
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
I'm now running Valvoline VR-1 racing SAE 60. If this stuff thins out too much, I'm out of options.
http://www.whitfieldoil.com/download...alBulletin.pdf
I just dumped out my EXACTLY 972 mile castrol gtx 10w-30 oil today and it was black. Smelled like fuel obviously but not terrible. Only 5 weeks of driving, which is mostly weekends.
Going to get that tested at blackstone, just waiting for my kit to come.
But dumped in some RP 1030 with their premix just to see whats the hype.
Could be mental but engine does seem "quieter". And dropped like 5 degrees in my water temp??? Is that possible? Seriously. It was 92 degrees today and i was boosting on the highway, a couple of 3rd gear pulls and a 4th gear pull. Stop and go etc, back on the highway and maintained a 185F cruising. Came to traffic and i got 195F with the fans on.
Yesterday it was pinned at 200-205F with the fans on when i was stuck in traffic. And this was with no prior boosting.
Hmmm.
Gonna perform 1000 miles on RP and get that tested as well.
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Follow-up email I received from Blackstone a few days ago:
My experience with fuel diltuion is that it degrades the viscosity of any oil (including synthetics) rapidly, then levels off. My plan with running SAE 60 is that is will drop to an equivalent 30-40w within a few hundred miles and (hopefully) stay there for the duration of a 2000 mile OCI.
Fuel dilution is quite normal in these rotary engines. Fuel dilution at this level is going to make short work of breaking down any type of oil. We would suggest running a 5W/40 in the winter, and then increasing the viscosity to 20W/50 during the hottest summer months. It would also be a good idea to try to drive on the highway as often as possible, in order to cook off any fuel dilution that may be building up in the oil.
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Here's the most recent report (Shell Rotella T 15w-40), posted on the left-most column. Note that the heaviest oil I had tested, posted at the far right (Amsoil 20w-50) did the best job of protecting my bearings for the longest period of time.
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You're basically saying no matter what oil you use, if its 10w30, its recommended to change every 1000 miles because it will be broken down?
For the people who much rather change at 3k, should go with a 50?
Because then the debate turns into fuel dilution vs actual metal protection. (bearings, turbos etc).
Would it rather be much better, even though its the most expensive option, would be to get the very best oil out there and change that every 1000-1500 miles??
Say idemitsu, brad penn, RP, etc etc??
Because if you go for one thing, you're almost sacrificing the other, and vice versa no??