Diesel Oil Analysis

Oil Sample Collection Procedures, Oil Analysis Results, & Analysis Information

Routine oil analyses are common in many industries and may be used to help detect an engine problem before it compounds into a serious failure as well as monitor oil condition to ensure the engine oil is changed at an appropriate time. An oil sample can be pulled before performing an oil change, or at any interval in-between. An oil analysis is performed by a specialized laboratory who, through a series of test procedures, will provide a breakdown of the various contaminants and metals suspended in your engine oil sample.

Oil analysis pump: Amsoil p/n G1206-EA
25 ft. replacement hose: Amsoil p/n G1571-EA
Oil analysis service, prepaid shipping: Amsoil p/n KIT01-EA

Collecting an Oil Sample for Analysis

The following procedures are specific to Amsoil's test pump and Oil Analyzers oil analysis services. Procedures may differ for alternative sampling products, laboratories, and/or sampling techniques.

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oil analysis sample collection kit

• A pump, hose, and collection bottle is required to perform an oil analysis. Amsoil offers all of these, including the oil analysis service itself. Note that the hose is NOT reusable - it must be discarded after taking an oil sample. Though the analysis test kit is purchased through Amsoil, it is performed by a third party and you do not have to be using Amsoil brand engine oil; they also test gear oil.


collecting oil sample

• Remove the dipstick from from the vehicle and lay it on a clean table/work bench. Stretch out the oil analysis hose and mark 1 to 2 inches beyond the length of the dipstick. Cut the oil analysis hose another 8 to 12 inches beyond this marker.

To clarify, the hose should be 10 to 14 inches longer than the dipstick. The mark on the hose should be 1 to 2 inches longer than the length of the dipstick. Do not insert the hose into the dipstick tube farther than this mark. If inserted too deeply, the oil analysis hose may become stuck. If oil will not suck through the tube, rotate it - the tubing may have some memory and may be pointing upwards out of the crankcase oil.

• Install the sample bottle on the collection pump, then the collection hose. Once everything is tightened down snug, insert the hose into the dipstick tube.

oil sample

• Pull on the suction pump lever and fill the oil sample bottle to the fill line. After oil reaches the line, pull the hose out of the dipstick tube - when the hose is removed from the crankcase oil it will suck air and the pump will stop filling the sample bottle.

• Follow the instructions for filling out the oil sample information form and mailing the sample. In our experience, results are published within a business week after the sample is received.

• Clean the pump with a clean rag and discard the oil sample hose as not to contaminate the next oil sample.

Oil Analysis Results

An analysis is fairly comprehensive (depending on the laboratory) and will identify a number of chemicals and metals found in your engine oil in addition to addressing the acceptable limits of said findings. They include, but are not limited to:

Wear metals, PPM - Wear metals include chromium, iron, and aluminum; materials that make up the various bearings, gears, pistons, camshaft, crankshaft, cylinder walls, and other moving parts of your engine that experience metal-on-metal contact. Values are typically given in PPM (parts per million).

Fuel dilution, % by volume - This identifies the amount of diesel fuel found in your engine oil. All engines will have some degree of fuel dilution. Excessive idling, bad injectors, worn injection pump (low injection pressure), and a bad ring seal all lead to excessive fuel dilution. Additionally, lugging an engine and performance modifications may contribute to greater degrees of fuel dilution. If fuel dilution exceeds acceptable limits, diagnostics should be performed to identify the root cause. Values are typically given in percent by volume (volume of diesel fuel relative to volume of engine oil).

Exhaust soot, % by volume - Like fuel dilution, exhaust soot enters to the crankcase by means of blowby. Some exhaust soot in the engine oil is entirely normal, thus the reason oil rapidly turns black in diesel engines. Anything that creates black smoke out of the tailpipe (performance modifications, worn injectors, etc) contributes to oil contamination. Values are typically given in percent by volume (volume of exhaust soot relative to volume of engine oil).

Water, % by volume - Water/engine coolant in the engine oil is the result of a failed seal, o-ring(s), water pump, head gasket, oil cooler, or EGR cooler. Values are typically given in percent by volume (volume of water/coolant relative to volume of engine oil).

Viscosity, Oxidation, & Nitration - This identifies the current viscosity of the engine oil, the degree of contamination, and the level of oil contamination/breakdown.

Oil Analysis Results and Oil Change Intervals

We never recommend extending OEM defined oil change intervals, regardless of the type/brand of oil used. However, using a professional oil analysis service is theoretically an appropriate technique for making adjustments to oil change intervals, whether that translates into shortening or lengthening them. Oil analysis services are employed in certain industries to gauge equipment condition as well as indicate an appropriate service interval. In certain instances, service costs can be reduced by relying on this method.

Oil Analysis Reports

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1995 C3500, 6.5L GM/Detroit Diesel

1991 F-250, 6.9L IDI Diesel

1996 F-250, 7.3L Power Stroke Diesel

6.5L GM diesel oil analysis report 6.9L/7.3L IDI diesel oil analysis results 7.3L Power Stroke diesel oil analysis results

The GMC passed an oil analysis with flying colors, which was expected. The truck only has 60,000 miles on the odometer, but it lives a hard life - it's unladen weight is 9,000 lbs, it's almost always loaded, and a cruising speed of 55 mph translates into 2,500 rpm as a result of its 4.63 : 1 rear end ratio

The IDI oil was tested shortly before it went into the shop for a new set of injectors. It's been smoking bad and has been "chugging' on startup. This truck is almost always hitched to a trailer. Mileage is in the 330,000 mile range. Fuel dilution and soot contamination was expected to be worse than the analysis revealed.

The oil analysis of this 140,000 mile Power Stroke came back alarming, however we simply forgot to disclose that the engine oil had a dose of Archoil oil additive.