Oil Question?
#4
Staging Lane
Join Date: Jun 2009
Location: South Houston, Texas
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Wow, unless you have a rotary T/A then theres no way he is a mechanic...
Conventional oil is good and all but it lacks some of the things that we, man, have added to the oil to advance its properties for engine oil use.
copy pasta from wikipedia...
Advantages
Measurably better low and high temperature viscosity performance
Better chemical & shear stability
Decreased evaporative loss
Resistance to oxidation, thermal breakdown and oil sludge problems
Extended drain intervals with the environmental benefit of less oil waste.
Improved fuel economy in certain engine configurations.
Better lubrication on cold starts
Disadvantages
Initial costs are usually two to four times greater than petroleum-based oils, though at one time, man-made oils cost ten times more than petroleum. Initial costs are often mitigated by extended change intervals, which individuals may confirm through used oil analysis.
The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was though. Many modern cars now come with synthetic oil as a factory fill.
Potential decomposition problems in certain chemical environments (industrial use dominantly)
Potential stress cracking of plastic components like POM (polyoxymethylene) in the presence of PAOs (polyalphaolefins).
Potential on some older pushrod race engines with roller lifters for the roller itself not to spin with camshaft movement, but rather slide while the roller itself remains either stationary or at a lower circumferential speed than that of the camshaft lobe.
Synthetics do not hold lead in suspension as well as mineral oil, thus caution is advised when the engine is run on leaded fuel. As an example, leaded fuel is still commonly used in aviation.
In July 1996, Consumer Reports published the results of a two year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular oil. In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high speed driving in extreme heat. But our test results relate to the most common type of severe service — stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." This research was criticized by some because most engine damage appears to be caused by cold starts, and their research method may not have included enough cold starts to be representative of personal vehicle use.
Synthetic oils are not recommended in automotive rotary engines.
Conventional oil is good and all but it lacks some of the things that we, man, have added to the oil to advance its properties for engine oil use.
copy pasta from wikipedia...
Advantages
Measurably better low and high temperature viscosity performance
Better chemical & shear stability
Decreased evaporative loss
Resistance to oxidation, thermal breakdown and oil sludge problems
Extended drain intervals with the environmental benefit of less oil waste.
Improved fuel economy in certain engine configurations.
Better lubrication on cold starts
Disadvantages
Initial costs are usually two to four times greater than petroleum-based oils, though at one time, man-made oils cost ten times more than petroleum. Initial costs are often mitigated by extended change intervals, which individuals may confirm through used oil analysis.
The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was though. Many modern cars now come with synthetic oil as a factory fill.
Potential decomposition problems in certain chemical environments (industrial use dominantly)
Potential stress cracking of plastic components like POM (polyoxymethylene) in the presence of PAOs (polyalphaolefins).
Potential on some older pushrod race engines with roller lifters for the roller itself not to spin with camshaft movement, but rather slide while the roller itself remains either stationary or at a lower circumferential speed than that of the camshaft lobe.
Synthetics do not hold lead in suspension as well as mineral oil, thus caution is advised when the engine is run on leaded fuel. As an example, leaded fuel is still commonly used in aviation.
In July 1996, Consumer Reports published the results of a two year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular oil. In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high speed driving in extreme heat. But our test results relate to the most common type of severe service — stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." This research was criticized by some because most engine damage appears to be caused by cold starts, and their research method may not have included enough cold starts to be representative of personal vehicle use.
Synthetic oils are not recommended in automotive rotary engines.
#5
Staging Lane
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I use synthetic in all of my vehicles and go between 6000-8000 miles between oil changes. I have experimented with the change interval by sending in oil samples and this range seems to be the best, at least for me. The initial cost is definately offset by being able to go longer between oil changes.
#7
12 Second Club
Check the performance rating on the next can of oil you buy. Good dino oils are currently rated SL and synthetics are the new SM rating. Basically the higher the better as far as sludge prevention, wear prevention etc.
Cut and paste from wearcheck.com
What does 'performance' mean & how is it measured ?
The API system (and others) originated when the engine manufacturers started communicating their needs to the oil companies. When an engine oil is blended,
many chemicals (additives) are added to the oil. Additives impart certain properties to the oil, enabling it to function in a desired manner when used to lubricate an engine. It is the additives which impart performance.
Some additives are listed below:
Additive Property
Antiwear Reduces wear and friction
Extreme pressure agent Prevents scoring and seizure
Corrosion inhibitor Prevents rusting
Detergent Keeps surfaces free of deposits
Dispersant Keeps deposits in suspension
Friction modifier Alters frictional properties
Pour point depressant Allows oil flow when cold
Seal swell agent Ensures seals do not leak
Viscosity index improver Allows viscosity stability
Antifoamant Retards foaming
Antioxidant Retards oil oxidation
Metal deactivator Retards catalytic oil oxidation
Simply put, the higher the API grade, the more additives the oil contains and the more performance tests it has passed.
Four stroke engine oils
The API system for four stroke engine oils has the following format: Sx/Cy where x and y denote the oil class. The full range is as follows:
Petrol Engine Diesel Engine
SA CA
SB CB
SC CC
SD CD
SE CE
SF CF (CF4)
SG CG4
SH
Two systems are used, one for petrol engines (S) and one for diesel engines (C). The 'S' stands for 'spark' and the 'C' for 'compression' indicating the different ignition methods and not 'service' and 'commercial' as is sometimes thought. A 'T' class is used for two stroke engines, but this is beyond the scope of this bulletin.
The 'best' oil might not be ideally suited to your engine. The secondary letter, A B C D, etc. denotes the performance of the oil. The further into the alphabet you go, the better the oil is. An SF oil outperforms an SD oil and a CE oil outperforms a CD oil. Most four stroke engine oils are graded for both diesel and petrol engines. The best oil for a diesel engine is a CG4 grade and the best oil for a petrol engine is an SH grade. Interestingly enough, although an SG oil has superior qualities to an SF oil, there is basically no difference between an SG and an SH oil for petrol engines.
Generally speaking, most oils have grades such as SF/CD where the C class (diesel engines) is lower than the S class (petrol engines). This is because the oil in a diesel engine is far more highly stressed than in a petrol engine.
All the lower API grades are now obsolete. If it were possible to obtain an SA/CA oil, it would be a straight mineral oil with no additives at all. Probably the lowest grade oil available today is an SC/CC oil. It is considered to be a 'running in' oil, as it has a low additive level and has not passed the performance tests that other top of the range oils have passed. This is the only time when the x/y letter suffix is the same.
Some of the API classifications have a suffix of '4' such as CF4 and CG4 (there is also a CD II specification). The CF4 class of oils was (and still is in some countries) an intermediate classification of high performance diesel engine oil (see "Oils used in clean-burn engines" for more details on these oils).
Cut and paste from wearcheck.com
What does 'performance' mean & how is it measured ?
The API system (and others) originated when the engine manufacturers started communicating their needs to the oil companies. When an engine oil is blended,
many chemicals (additives) are added to the oil. Additives impart certain properties to the oil, enabling it to function in a desired manner when used to lubricate an engine. It is the additives which impart performance.
Some additives are listed below:
Additive Property
Antiwear Reduces wear and friction
Extreme pressure agent Prevents scoring and seizure
Corrosion inhibitor Prevents rusting
Detergent Keeps surfaces free of deposits
Dispersant Keeps deposits in suspension
Friction modifier Alters frictional properties
Pour point depressant Allows oil flow when cold
Seal swell agent Ensures seals do not leak
Viscosity index improver Allows viscosity stability
Antifoamant Retards foaming
Antioxidant Retards oil oxidation
Metal deactivator Retards catalytic oil oxidation
Simply put, the higher the API grade, the more additives the oil contains and the more performance tests it has passed.
Four stroke engine oils
The API system for four stroke engine oils has the following format: Sx/Cy where x and y denote the oil class. The full range is as follows:
Petrol Engine Diesel Engine
SA CA
SB CB
SC CC
SD CD
SE CE
SF CF (CF4)
SG CG4
SH
Two systems are used, one for petrol engines (S) and one for diesel engines (C). The 'S' stands for 'spark' and the 'C' for 'compression' indicating the different ignition methods and not 'service' and 'commercial' as is sometimes thought. A 'T' class is used for two stroke engines, but this is beyond the scope of this bulletin.
The 'best' oil might not be ideally suited to your engine. The secondary letter, A B C D, etc. denotes the performance of the oil. The further into the alphabet you go, the better the oil is. An SF oil outperforms an SD oil and a CE oil outperforms a CD oil. Most four stroke engine oils are graded for both diesel and petrol engines. The best oil for a diesel engine is a CG4 grade and the best oil for a petrol engine is an SH grade. Interestingly enough, although an SG oil has superior qualities to an SF oil, there is basically no difference between an SG and an SH oil for petrol engines.
Generally speaking, most oils have grades such as SF/CD where the C class (diesel engines) is lower than the S class (petrol engines). This is because the oil in a diesel engine is far more highly stressed than in a petrol engine.
All the lower API grades are now obsolete. If it were possible to obtain an SA/CA oil, it would be a straight mineral oil with no additives at all. Probably the lowest grade oil available today is an SC/CC oil. It is considered to be a 'running in' oil, as it has a low additive level and has not passed the performance tests that other top of the range oils have passed. This is the only time when the x/y letter suffix is the same.
Some of the API classifications have a suffix of '4' such as CF4 and CG4 (there is also a CD II specification). The CF4 class of oils was (and still is in some countries) an intermediate classification of high performance diesel engine oil (see "Oils used in clean-burn engines" for more details on these oils).
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#8
TECH Fanatic
iTrader: (18)
Im not sure how accurate this is, but I recall hearing that synthetic oils can cause leaks that otherwise wouldnt be there with regular conventional oils. Something about synthetic being more thin. If you have a higher-milage car thats used conventional oil all its life, its possible switching to synthetic can outline problems. However the oil itself would not be the reason for problems, it would just point out existing problems more then regular oil.
#9
Staging Lane
Join Date: Jun 2009
Location: South Houston, Texas
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Im not sure how accurate this is, but I recall hearing that synthetic oils can cause leaks that otherwise wouldnt be there with regular conventional oils. Something about synthetic being more thin. If you have a higher-milage car thats used conventional oil all its life, its possible switching to synthetic can outline problems. However the oil itself would not be the reason for problems, it would just point out existing problems more then regular oil.
#19
TECH Fanatic
iTrader: (7)
Tell your mechanic that ummmm my car came stock with Mobil 1 5W-30. So did the camaros, all GM V8 trucks, CTS-Vs, GTOs, and all vettes. That means he is a GM engineer then. Say something like that, don't recommend going back to that retard if I where you If he has been putting conventional motor oil in your car, and you have any oil leaks. Blame him!!!