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| » How do you judge when the oil needs to be drained out? |
The possible reasons for oil needing to be changed in the field are:
- Depletion of additive in the oil as can be judged by the blotting paper tests or the TBN availability test (especially for diesel oils).
- Dilution of the oil by fuel seeping into the oil circulation system. The oil tends to become less viscous and smells burnt.
- Excessive oil oxidation or heavy contamination of the oil with soot (which could happen while operating in stop-go conditions, hilly terrain or heavily overloaded conditions. The oil also turns very black.
The best way to judge whether the oils life is exhausted is to actual test a sample in the lab, if the viscosity has increased or decreased substantially (please also refer the question on rejection limits) or the TBN has decreased a lot from its starting value, the oil needs to be changed.
On the field, since it is not immediately possible to test the oil, please look at the following warning signals
- Oil has turned black
- Oil emits a burnt odour
- Oil’s viscosity (judged by rubbing the oil between the fingers) has increased or decreased substantially.
Please note that these are only possible warning signals but do not necessarily confirm that the oil is bad. If you suspect that the oil is bad, take a sample and send the oil to the lab for analysis.
We have already mentioned about the “Blotter Paper” test, the following may help interpreting the results. |
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| We advise that final judgment should not be made about the oil till the time it is checked in the laboratory. Under normal circumstances, users should only be guided by the concerned vehicle manufacturer’s recommendation for that particular grade of oil. |
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| » If the used oil sample oil is black in colour, does it need to be changed immediately? |
The detergent in the oil functions as a clean up/keep clean agent while the dispersant enables the oil to keep insoluble dirt particles in suspension. If the engine is already dirt clogged, use of good engine oil will result in a lot of the earlier dirt being cleaned off the engine and being kept in suspension. Thus, while the oil is actually performing its job well, a cursory look at a sample of the oil may seem to indicate that the oil has abnormally blackened and needs to be rejected, which is, in reality, a wrong judgment.
Two things need to be done if the oil seems very black. Conduct the blotting paper test to see if the oil has the power to keep the dirt continuously in suspension. Secondly, feel the oil to check its viscosity. If it feels abnormally thick, it is possible that the oil has oxidized and, therefore, you are advised to send a sample of the oil to the lab for analysis. |
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| » If the used oil sample smells burnt, is the oil bad? |
| If the oil smells burnt, it is possible that some fuel has contaminated the oil. Check to see if the oil also feels thin and if so, send the sample of oil to the lab for verification. The oil needs to be changed only if there is substantial fuel dilution, resulting in a viscosity drop of greater than 15% of its original value. If the viscosity drop is not so substantial, the oil can continue to be used, as a certain amount of fuel dilution (below 4%) is not abnormal. But inform the vehicle owner about this fact and request him to get his truck engine checked. |
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| » What benefits can I expect from Multigrade oils? |
Multigrade oil, basically, is oil whose viscosity properties have been changed artificially in order to slow down its rate of change of viscosity with temperature. Thus, multigrade oils tend to be thinner at low temperatures and thicker at high temperatures than monograde oil.
There are several benefits one may expect of multigrade oil.
- When a car is at rest for a few hours, all the engine oil comes down to the oil sump. Thereafter, as soon as the car is started there is a certain time (probably only microseconds) before the oil reaches all the parts of the engine once again. Since the multigrade oil is thinner at low temperatures, it reaches all parts of the engine quicker than monograde oil and hence, reduces wear to that extent.
- Generally, it has been observed that use of multigrade oils enables better fuel economy of 1.5% - 3%.
- Multigrade oil offers better protection to the engine at high temperatures than monograde oil, since it is thicker than the monograde oil at temperatures above 100OC. This is so even if the multigrade oil is thinner than the monograde oil at temperatures below 100OC. This property of multigrades also reduces oil consumption.
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| » If oil is thinner than another oil at room temperature, does it imply that it will give less protection to the engine at high temperatures? |
| No, because the two oils may have different Viscosity Indices. In other words, the two oils may have different rates of change of viscosity with temperature. Thus, oil with a
higher VI may have a higher viscosity at a high temperature than oil with a lower VI, even if the later has a higher viscosity at room temperature. |
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| » Is red oil better than natural golden color oil? |
| No, since the red colour is from a dye, and not from any performance or protection additive. |
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| » How do I know if there is water in the oil? |
| Heat the oil for some time, if the oil crackles, there is water in oil. If contamination is high, the oil
colour will also change. |
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| » What are the normally used rejection limits for engine oils? |
Generally, the rejection limits used are
TBN - If the TBN falls to less than 1/2 its original value of less than 3 mg KOH/g, whichever is lower, the oil has to be rejected.
Viscosity - If the viscosity of the used oil is 25% more than the fresh oil viscosity or 15% lesser than the fresh oil viscosity, the oil has to be rejected. |
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| » Is it correct to add oil to a fuel tank in a four-stroke engine vehicle? |
| No, because the oil is not easily burnt and tends to leave a lot of deposits on the engine parts preventing it from functioning well. |
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| » How is a seizure caused? |
A seizure could be caused by little or no lubricant being present in the system, due to leakage or over consumption, resulting in friction causing overheating of the engine parts, which, in turn, causes micro welds in the engine, resulting ultimately in seizure of the engine. The seizure could also be caused by over thinning of the oil, due to fuel dilution.
However, more often than not, operational problems and not the oil cause the seizure. For instance, the seizure could also be caused by running an overloaded truck for a long period of time resulting in overheating. Alternatively, if the engine becomes overheated, for any other reason also (for instance, if the cooling system is not working properly), the engine could still seize.
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| » What are the possible reasons for an oil pressure drop? |
During the normal operation of a vehicle, the oil also serves as a sealant by virtue of its viscosity. This effectiveness of the oil is reflected in the oil pressure gauge. If the oil pressure is seen to go down, it could have reduced for several reasons.
Firstly, it is possibly because the oil has thinned down considerably, due to fuel dilution. Secondly, it could be because of insufficient oil in the system, either because of an oil leakage or excessive oil consumption or even possible oil pump failure, causing the oil to not circulate. Check the oil for fuel dilution and check the oil level in the sump.
While checking the level of the oil in the oil sump, ensure that the vehicle has been at rest for 3-4 hours, which will enable all the oil to flow down into the sump. If both seem all right, then check the vehicle for pump failure or any other hardware related problem. |
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| » What is the cause for excessive oil consumption? |
One of the primary reasons for excessive oil consumption is external oil leakages from areas like tappet cover, oil filter bowl, timing cover oil seal, rear main oil seal (flywheel side) or at some other point in the oil circulation system. Therefore, this is the first reason one has to eliminate before proceeding further to investigate the probable causes for high oil consumption.
During a normal four-stroke vehicle operation, the vehicle is not supposed to consume oil. However, during the process of combustion when the piston moves up and down, a little oil gets thrown into the combustion chamber, which results in it also being burnt. Generally, if an oil is very thin at the operating temperature, it gets thrown up more often into the cylinder, thus, resulting in it being burnt and consumption going up. Thus, one of the reasons for oil consumption is also the thinning of the oil due to fuel dilution.
Oil consumption can also be engine hardware related. If the clearances between the piston and the cylinder are excessive, this can cause high oil consumption. |
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| » I converted the customer from 'Company X' to Valvoline and the customer reported sudden increase in oil consumption. Is my product at fault? |
This classic complaint can happen in 5-10% cases when changing brands of motor oils. This has been occurring for years, and can occur when changing from one brand to the other (same company), as well as one company to another.
Remember, in all such changes, increase in consumption of oil is observed for a short period of time (1-2 change intervals), and then returns to the previous low level. Interestingly, if one returns to the original brand, higher oil consumption is again observed!
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| » Can we mix two different brands of engine oils? |
| Technically it is possible to do so provided the new oil has the same performance level as the old oil. However, mixing oil brands (read topping-up) on a continuous basis is not a good idea. You should also be aware that engines typically go through a period of adjustment when making the transition from one oil to another. Because brands could be formulated with different additive chemistries, a new brand may act differently than the old one at first. Increased oil consumption and leaking seals are common adjustment problems. |
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| » Can we add extra additives in oil? |
No, In fact, it may be harmful.
All engine oils that meet current API standards already have additives in them. These additives have been selected and balanced to meet engine manufacturers’ performance requirements, which have been set by a working association with API, SAE and ASTM testing standards.
Some OEM’s even go as far as saying that using a supplemental additive or engine treatment may void the engine warranty.
In recent years, engine treatments with suspended Teflon® have been introduced. These products claim to bond to engine surfaces, reducing friction for better power and fuel economy. However, Teflon only bonds to engine surfaces at extremely high temperatures. No oil-wetted engine surfaces reach those temperatures.
To date, there is not seen any data that show that supplemental additives offer any benefit. Both VI improvers and Teflon show no improvement in engine tests.
Bottom line is that supplemental oil additives add nothing but extra cost. |
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| » Why does oil leak from grease? |
Greases are like oil soaked sponge and are meant to release oil at a certain rate, depending on the operating conditions. Theoretically, oil is not meant to be released during rest periods or during storage periods. However, in practice, a certain amount of oil does leak from the grease even during rest periods or during storage. As long as this leakage is not excessive, this can be considered normal.
Generally, excessive separation of oil from the grease during storage, as indicated by a thick layer of oil on top of the grease, a sign that the grease has not been ‘cooked’ well, resulting in the oil not being fully retained by the grease.
While removing grease from a pack, it is preferably not to remove grease only from the centre or one side alone, resulting in a massive `cavity’ existing in the centre or the side of the pack from which the grease has been removed. This is because a cavity of this sort results in the oil separating from the grease on the sides of the cavity and forming a pool in the cavity. While removing grease from a pack try to remove it uniformly from all sides.
Generally, it is not advisable to cram the bearing housing with grease, as this could result in overheating, leakage and a possible seizure due to the non-availability of adequate oil. Preferably, pack only half or a third of the housing with grease. |
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| » Are there any correct methods to store drums? |
Yes, there are certain procedures to be followed while storing drums, especially in depots, where they could be stored over long periods of time.
Storage of oil drums - Normally an oil drum stored vertically has a certain gap between the top oil level in the drum and the top of the drum. This gap is air-filled. During the daytime, particularly in hot regions, the oil expands causing air to be pushed out of the drum. At nighttime, the oil shrinks causing air to be breathed into the drum. If there is a lot of humidity in the air or a layer of water on the drum, there is ingress water into the drum, which settles down slowly in the drum. To avoid this, the drum should always be stored horizontally with the oil level higher than both vents which would be at the 3.0’ clock and 9.0’ clock positions as shown below. |
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Generally, it is always better to store the drums on wooden blocks (dunnings) to prevent rusting of the part in contact with the ground.
Storage of grease drums - Store grease drums vertically and cover the top of the drums with a tarpaulin to prevent breathing.
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| » A Customer changes Gear oils only after he feels hard shift or some break down. Is it really necessary to change these at regular intervals like engine oils? |
| Gear oils should definitely be changed at regular intervals. Though not easily seen, gear oils & axle oils are most prone to external contaminants like dust, water which accelerate gear wear & is most common cause of vehicle break down which is not only costly affair but is also an unavoidable. |
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| » Why do turbo charged vehicles require special engine oil? |
| Turbo charged vehicles result in better fuel combustion thereby increasing thermal load on engine oil. Soot production is increased. Therefore higher quality engine oil is needed for such applications. |
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| » How is bad quality fuel related to an Engines Oils’ performance? |
- Bad quality / Adulterated fuel results in improper combustion. This affects the engine performance & load on it increases dramatically which affects oil performance.
- Also, by products of improper combustion, has a chance of going into sump & damaging the composition of lubricant. This affects the overall performance.
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