- Joined
- Jul 26, 2021
- Messages
- 31
Attached are two reports, one from TestOil and the other from BlackStone Labs. Long write up on observations, testing and measurements. 12 samples were taken over 10k miles
This engine has a history of suffering from GDI fuel dilution and soot build up, causing excessive timing chain wear, and stuck rings, leading to oil consumption and other related problems. Original OLM algorithm could take the oil beyond 10k miles, and the original SN Dexos 1 synthetic blen oil spec was not up to the the job. Previous generation of Ecotec engine with PFI showed very low fuel dilution levels and acceptable wear rates, long life. Hundreds of sample reports and rates provided by BSL were 2 - 2.5ppm of Iron/1k miles. The introduction of GDI to the second generation, fuel dilution increase to 3-5%, and even higher 7%+ during cold operation. Wear rates doubled to over 5ppm/1k. The average for both generations combined for the past 20 years is 3.5ppm/1k miles.
Over the past three years I have experimented with different oils, viscosity, addition of a by-pass filter, and changes to the PCV system to reduce the affects of the fuel and soot. I also started performing near full volume oil changes to reduce the residual oil affects. These engines can retain 15-20% of residual oil and confirmed by oil analysis and BSL.
This latest 10k mile OCI consisted of 98% highway driving, 1k/wk. 2 drive cycles and 200 miles/day. During this time I experimented with the affects fuel types and octane, switching after two full tanks. I wanted to see if it affected overall fuel dilution, wear rate and soot loading. I had tried the Amsoil SS 5W-30 API SN+, Dexos 1 Gen 2 oil the previous year and saw comparable fuel contamination that caused viscosity loss beyond the 30 weight range, and double the wear rates. I was also driving the same route, distance and percentage of highway driving using Top Tier, 93 Octane non-ethanol fuel.
At the beginning of the OCI I removed the bypass filter, drained the sump and circulated 4.5 quarts of 0W-40 in the engine, and drained again and added 5qts and full flow (Mobil 1 Extended Life) and new bypass filter . I estimated less than 2% residual oil remained. It shows blending of the fluids in the some of the additive levels(increase and decrease) viscostiy, TBN reading, fuel dilution after the first 25 mile sample. Each sample was taken by vacuum pump through the dipstick, drawing from the top half of the sump after a highway run and normal engine temp. A reference sample of the new oil was taken and included in the report.
The first 1000 miles some cleaning affect I presume of the new oil from increase in particulate count. The new filters will improve in efficiency as time goes on. No wear metals detected from residual oil or engine operation in this sample period. Viscosity dropped by 1cSt (now in a high 30 weight range), one point decrease in TBN, and fuel dilution of 2.7%. Using TT 93 Octane, non ethanol, very little knock retard, low carbon deposits on pistons.
3k mile sample, switched to a TT 91 octane, non-ethanol fuel, Recorded increase in engine load, decrease in engine timing and more knock retard. Small additional carbon on pistons. Slight decrease in some additive levels, 3x decrease in particulate count as filters cleaned up the oil. Increase in oxidation from 9-13, slight decrease in viscosity, 1.5 point decrease in TBN, fuel dilution still in the 2% range. Wear rate for Iron is less than 1ppm/1k miles which is half that of using 5W-30 of same brand and quality of oil.
4k mile sample, fuel was TT 93 octane with E10, improved Knock retard but piston carbon changed in spray patterns and slight increase. Half way through this run added .25 qts to make up for the loss from samples, and slight oil consumption. Minor affects on additive levels, oxidation remained the same due to addition of oil. Particle count stabilized at 600 range at >4 microns. .6 cSt decease in viscosity, slight decrease in TBN even with added oil. Fuel dilution increased above 3%. Iron wear rate holding at 1ppm/1k miles.
5k mile sample, switched back to TT 93 Octane, non ethanol, very low knock retard, high ignition timing. Reduced carbon and and narrow spray pattern than before. Small decrease in additive levels. Normal increase in oxidation. Particle count stable and clean. Viscosity about the same at 11.2 cSt. TBN is decreasing predictably as it controls acids. Fuel dilution dropped below 3%. Iron wear rate holding at 1ppm/1k miles.
6k mile sample, switched to 89 octane, non ethanol fuel. Increase in engine knock retard, lower ignition advance. Increase in carbon, and changes in spray pattern. Minor changes in additive levels. Oxidation about the same. Particle count slight up tick. Viscosity is stable at 11.1. TBN another .5 point decrease. Fuel dilution is holding at around the 3% level. Iron wear rate holding at 1ppm/1k miles.
7k mile sample, TT 91 Octane, ethanol. Knock retard and carbon levels about the same as previous. Small decreases in additive levels, oxidation slight increase, decrease in particle count. Viscosity is holding steady at 11.3 cSt. TBN another small decrease. Fuel dilution decreased to 2.6%. Iron wear rate not much change.
8k mile sample, TT 93 octane, Non Ethanol fuel, very low knock retard recorded. Small changes in additive levels, oxidation increase, low particulate levels. Viscosity showing a slight increase, possible due corresponding increase in oxidation. TBN another .6 point decrease. Fuel dilution is holding at below the 3% level. Iron wear rate holding at 1ppm/1k miles.
9k mile sample, switched to TT, 87 octane with E10, high engine knock retard, lower ignition advance, increase in engine load. HIgh carbon build up covering most of the pistons and evidence of pre-ignition. Switched back to TT 93 Octane, non ethanol after one tank. Carbon reduced significantly, performance improved. High amounts of particulates still in the oil. Added .25 qts of oil to make up for samples and minor consumption. Lower viscosity, .6 point increase in TBN, increase in additive levels. Reduction in oxidation levels. Fuel dilution increased to 4%, but Iron wear rate still holding at about 1ppm/1k miles.
10.5k mile sample, kept using TT, 93 Octane, non ethanol. decrease in carbon build up, improved performance, low engine knock retard. Low particulate count, oxidation and viscosity levels about the same, another small decrease in TBN, fuel dilution remains at 4%, and iron wear levels remain at the 1ppm/1k miles. A Analytical Ferrography test was completed at no extra charge. Showed very low amounts of contaminants from rubbing wear and dust/dirt in the 5-15 micron range. The Mobil1 full flow filter was removed, drained of oil and media removed and examined, only a few fragments of a metal, barely visible to the eye. Only 20% of the surface area contained visible carbon build up. All media intact. A Fram Ultra filter was installed in its place. Plan to continue with this OCI.
The engine has 150k miles. The pistons, rings and timing chain was replaced at 90k by GM. Cylinder head was cleaned and exhaust valves and seats were re-ground, new valve stem seals. The engine continues to show factory compression in all cylinders, and consistently higher fuel efficiency when new. No varnish, gum, or sludge found on the cylinder head. The first 80k resulted in heavy varnish, black sludge, and coking of the interior surfaces. Wear and slippage of the chains. All pistons showed heavy carbon build up, and sticking rings, and bore was honed to mirror like finish, no cross hatch remained.
Based on winter time fuel dilution levels showing 7-10%, the OCI will be cut in half or until viscosity drops out of spec, wear rate increases, and/or TBN becomes depleted.
I have included a BSL report on the engine oil at 9600 miles. The Wear and additive levels are nearly identical, along with viscosity and TBN. The particle count was much different as they used optical scan instead of pore blockage test. Optical is not accurate in dark engine oils. I sent another sample, and they tested using pore blockage and the results were very close to TestOil results. Fuel Dilution using their Cleveland Open cup method consistently shows lower fuel concentrations than the common used Gas Chromatography test by other labs. I have repeated this comparison several times over the past few years. If you have a GDI engine and fuel dilution is possible, recommend GC. The costs for the full report from TestOil, with the additional TBN, Oxidation, Fuel Dilution, Particle Count and AF is only $40 with same day results in most cases.
In addition to the reduced carbon build up, near elimination of engine knock, improved engine performance with the Premium, non ethanol fuel, I was able to see a 2 mpg average increase over the minimum spec TT 87 octane, E10 fuel. I did not see any increased wear rates in any of the engine metals at the beginning of OCI, and likely not until after 2k miles, whether caused by residual oil contaminants or any affect that the near 98% new engine oil may have on the load bearing components of the engine. FInally, I used basic radial chromatography blotter test at each sample and could not show any noticeable contaminents or change in oil color until 4k miles.
This engine has a history of suffering from GDI fuel dilution and soot build up, causing excessive timing chain wear, and stuck rings, leading to oil consumption and other related problems. Original OLM algorithm could take the oil beyond 10k miles, and the original SN Dexos 1 synthetic blen oil spec was not up to the the job. Previous generation of Ecotec engine with PFI showed very low fuel dilution levels and acceptable wear rates, long life. Hundreds of sample reports and rates provided by BSL were 2 - 2.5ppm of Iron/1k miles. The introduction of GDI to the second generation, fuel dilution increase to 3-5%, and even higher 7%+ during cold operation. Wear rates doubled to over 5ppm/1k. The average for both generations combined for the past 20 years is 3.5ppm/1k miles.
Over the past three years I have experimented with different oils, viscosity, addition of a by-pass filter, and changes to the PCV system to reduce the affects of the fuel and soot. I also started performing near full volume oil changes to reduce the residual oil affects. These engines can retain 15-20% of residual oil and confirmed by oil analysis and BSL.
This latest 10k mile OCI consisted of 98% highway driving, 1k/wk. 2 drive cycles and 200 miles/day. During this time I experimented with the affects fuel types and octane, switching after two full tanks. I wanted to see if it affected overall fuel dilution, wear rate and soot loading. I had tried the Amsoil SS 5W-30 API SN+, Dexos 1 Gen 2 oil the previous year and saw comparable fuel contamination that caused viscosity loss beyond the 30 weight range, and double the wear rates. I was also driving the same route, distance and percentage of highway driving using Top Tier, 93 Octane non-ethanol fuel.
At the beginning of the OCI I removed the bypass filter, drained the sump and circulated 4.5 quarts of 0W-40 in the engine, and drained again and added 5qts and full flow (Mobil 1 Extended Life) and new bypass filter . I estimated less than 2% residual oil remained. It shows blending of the fluids in the some of the additive levels(increase and decrease) viscostiy, TBN reading, fuel dilution after the first 25 mile sample. Each sample was taken by vacuum pump through the dipstick, drawing from the top half of the sump after a highway run and normal engine temp. A reference sample of the new oil was taken and included in the report.
The first 1000 miles some cleaning affect I presume of the new oil from increase in particulate count. The new filters will improve in efficiency as time goes on. No wear metals detected from residual oil or engine operation in this sample period. Viscosity dropped by 1cSt (now in a high 30 weight range), one point decrease in TBN, and fuel dilution of 2.7%. Using TT 93 Octane, non ethanol, very little knock retard, low carbon deposits on pistons.
3k mile sample, switched to a TT 91 octane, non-ethanol fuel, Recorded increase in engine load, decrease in engine timing and more knock retard. Small additional carbon on pistons. Slight decrease in some additive levels, 3x decrease in particulate count as filters cleaned up the oil. Increase in oxidation from 9-13, slight decrease in viscosity, 1.5 point decrease in TBN, fuel dilution still in the 2% range. Wear rate for Iron is less than 1ppm/1k miles which is half that of using 5W-30 of same brand and quality of oil.
4k mile sample, fuel was TT 93 octane with E10, improved Knock retard but piston carbon changed in spray patterns and slight increase. Half way through this run added .25 qts to make up for the loss from samples, and slight oil consumption. Minor affects on additive levels, oxidation remained the same due to addition of oil. Particle count stabilized at 600 range at >4 microns. .6 cSt decease in viscosity, slight decrease in TBN even with added oil. Fuel dilution increased above 3%. Iron wear rate holding at 1ppm/1k miles.
5k mile sample, switched back to TT 93 Octane, non ethanol, very low knock retard, high ignition timing. Reduced carbon and and narrow spray pattern than before. Small decrease in additive levels. Normal increase in oxidation. Particle count stable and clean. Viscosity about the same at 11.2 cSt. TBN is decreasing predictably as it controls acids. Fuel dilution dropped below 3%. Iron wear rate holding at 1ppm/1k miles.
6k mile sample, switched to 89 octane, non ethanol fuel. Increase in engine knock retard, lower ignition advance. Increase in carbon, and changes in spray pattern. Minor changes in additive levels. Oxidation about the same. Particle count slight up tick. Viscosity is stable at 11.1. TBN another .5 point decrease. Fuel dilution is holding at around the 3% level. Iron wear rate holding at 1ppm/1k miles.
7k mile sample, TT 91 Octane, ethanol. Knock retard and carbon levels about the same as previous. Small decreases in additive levels, oxidation slight increase, decrease in particle count. Viscosity is holding steady at 11.3 cSt. TBN another small decrease. Fuel dilution decreased to 2.6%. Iron wear rate not much change.
8k mile sample, TT 93 octane, Non Ethanol fuel, very low knock retard recorded. Small changes in additive levels, oxidation increase, low particulate levels. Viscosity showing a slight increase, possible due corresponding increase in oxidation. TBN another .6 point decrease. Fuel dilution is holding at below the 3% level. Iron wear rate holding at 1ppm/1k miles.
9k mile sample, switched to TT, 87 octane with E10, high engine knock retard, lower ignition advance, increase in engine load. HIgh carbon build up covering most of the pistons and evidence of pre-ignition. Switched back to TT 93 Octane, non ethanol after one tank. Carbon reduced significantly, performance improved. High amounts of particulates still in the oil. Added .25 qts of oil to make up for samples and minor consumption. Lower viscosity, .6 point increase in TBN, increase in additive levels. Reduction in oxidation levels. Fuel dilution increased to 4%, but Iron wear rate still holding at about 1ppm/1k miles.
10.5k mile sample, kept using TT, 93 Octane, non ethanol. decrease in carbon build up, improved performance, low engine knock retard. Low particulate count, oxidation and viscosity levels about the same, another small decrease in TBN, fuel dilution remains at 4%, and iron wear levels remain at the 1ppm/1k miles. A Analytical Ferrography test was completed at no extra charge. Showed very low amounts of contaminants from rubbing wear and dust/dirt in the 5-15 micron range. The Mobil1 full flow filter was removed, drained of oil and media removed and examined, only a few fragments of a metal, barely visible to the eye. Only 20% of the surface area contained visible carbon build up. All media intact. A Fram Ultra filter was installed in its place. Plan to continue with this OCI.
The engine has 150k miles. The pistons, rings and timing chain was replaced at 90k by GM. Cylinder head was cleaned and exhaust valves and seats were re-ground, new valve stem seals. The engine continues to show factory compression in all cylinders, and consistently higher fuel efficiency when new. No varnish, gum, or sludge found on the cylinder head. The first 80k resulted in heavy varnish, black sludge, and coking of the interior surfaces. Wear and slippage of the chains. All pistons showed heavy carbon build up, and sticking rings, and bore was honed to mirror like finish, no cross hatch remained.
Based on winter time fuel dilution levels showing 7-10%, the OCI will be cut in half or until viscosity drops out of spec, wear rate increases, and/or TBN becomes depleted.
I have included a BSL report on the engine oil at 9600 miles. The Wear and additive levels are nearly identical, along with viscosity and TBN. The particle count was much different as they used optical scan instead of pore blockage test. Optical is not accurate in dark engine oils. I sent another sample, and they tested using pore blockage and the results were very close to TestOil results. Fuel Dilution using their Cleveland Open cup method consistently shows lower fuel concentrations than the common used Gas Chromatography test by other labs. I have repeated this comparison several times over the past few years. If you have a GDI engine and fuel dilution is possible, recommend GC. The costs for the full report from TestOil, with the additional TBN, Oxidation, Fuel Dilution, Particle Count and AF is only $40 with same day results in most cases.
In addition to the reduced carbon build up, near elimination of engine knock, improved engine performance with the Premium, non ethanol fuel, I was able to see a 2 mpg average increase over the minimum spec TT 87 octane, E10 fuel. I did not see any increased wear rates in any of the engine metals at the beginning of OCI, and likely not until after 2k miles, whether caused by residual oil contaminants or any affect that the near 98% new engine oil may have on the load bearing components of the engine. FInally, I used basic radial chromatography blotter test at each sample and could not show any noticeable contaminents or change in oil color until 4k miles.
