Do you mix motor oils--grade? brand? type?

I only mix when it is time to clean up the leftover quarts of oil. I am currently on a leftover mix of 3 quarts of Mobil 1 0W40, one quart of Mobil 1 5W30, and one quart of German Castrol 0W30 in a turbocharged Saab engine.

I would question your use of the Redline ester. Ester has a high affinity for the metal surfaces and may interfere with / displace the ZDDP and other antiwear additives in the hydrocarbon based oils. Esters may actually outcompete the additives for space on the metal wear surfaces, and reduce the efficiency of the additives. In a sliding contact it may make no difference, but in a slapping contact the ester will be pushed out of the way and allow more metal - metal contact (due to the lower pressure viscosity characteristics of the ester basestock - inversely related to the temperature viscosity index of the base oil). The additives form thicker films on the metal wear surfaces and are not pushed out of the way as easily as a thinner ester based oil. High viscosity complex ester additives (as in German Castrol) are likely to remain in place better than an ester basestock.

I've seen compressors running on ester lubricants that exhibit wear in different places than the same compressor running on mineral oil. The differences were due to way the lubricant behaved in slapping contacts, or in other low velocity contacts like the top dead center piston / cylinder wall contact.

You make a good point re displacement of ZDDP by ester. It apparently is not an issue when running straight Redline, so I am wondering if the small quantity of Redline in the mix is a non issue, or is just enough ester to interfere with the lower zddp levels in typical motor oil (below 1000 ppm, whereas Redline is around 1400 ppm. Yet there have been good used oil analyses on mixes of one quart Redline with the rest Mobil 1.

That is no coincidence the level of ZDDP is higher in the Redline. You need to put a higher concentration of additive in the oil to allow it to get to the correct concentration on the metal surface. The additive has to fight its way through the ester to get to the metal surface and needs a concentration boost to get there.

I also wonder if the viscosity index modifiers will be affected by the ester as well. The VI improvers are normally polymers with polar groups present (acrylics, ethers. etc.) and the ester's higher polarity may change the way the polymer chain folds or unfolds in the non-polar hydrocarbon oil.

At the very least, you are running an oil system that was not originally considered by the people formulating the additive package for the hydrocarbon oils you are mainly using. It may work well, or you may see some unexpected things happen if you go too far outside the boundaries where the addivie formulation is known to work. The additive formulation for an ester based oil will be different from the additive package in a hydrocarbon based oil.

Pure ester is a much better base lubricant than the hydrocarbons because of the metal affinity and increased thermal stability, but small amounts of ester may cause unpredictable results (maybe good, maybe not so good). You will not see the benefits of the ester's thermal stability because of the presence of the hydrocarbon oil (the weakest link will break first).

quote:

Originally posted by refrig guy:
The additive formulation for an ester based oil will be different from the additive package in a hydrocarbon based oil.

Esters are hydrocarbons too. They just happen to be a little more complex in that, while the structure is the same as hydrocarbons, there is a substitution of atoms of another element for part of the hydrocarbon; hence, they are called substituted hydrocarbons. The bottom line is both are carbon based. Unlike a silicon based lubricant, which cannot be mixed with a carbon based lubricant and would not work in an internal combustion engine crankcase because of the hydrocarbon contamination from unavoidable blowby of fuel and fuel byproducts into the crankcase.

Paul, esters are not substituted hydrocarbons. Hydrocarbons contain only carbon and hydrogen, hence, hydrocarbons. Paraffinic oils are linear hydrocarbons, isoparaffins are branched hydrocarbons. Esters contain oxygen in the molecule, and it makes a significant difference in the properties of the compound. In the fuel world, esters could be called oxygenates. Substituted hydrocarbons may have a different element replacing one of the hydrogens, like chlorine or fluorine. The oxygen on the ester is not substituting for any hydrogens, it is incoporated into the molecular backbone of the compound between carbon atoms. I spent all those years in chemistry classes, they must be good for something (-:

Additive systems will respond differently in an ester environment than in a hydrocarbon environment due to the solubility differences between hydrocarbons and oxygenates. Hydrocarbons are very poor solvents, and many additives are polar compounds, and are only sparingly soluble in the non-polar hydrocarbons. This makes the additive more likely to go to the metal surface which is more polar than the hydrocarbon oil. The higher polarity of the esters makes the additive system perform differently, and changes will need to be made to the additive system to compensate.

As an aside, many gasoline additives are not very soluble either in the hydrocarbon fuels, and need an oxygenated carrier to keep them in solution. The carriers are only added at a fraction of a percent, but that is enough to affect the solubility of the additives.

I have not had much chemistry. That the ester is a substituted hydrocarbon is from a chemistry book, but perhaps I misunderstood the book. I see also on this web site it notes how the ester includes hydrocarbons:

quote:

The ester functional group is similar to that of an acid, except that the hydrogen atom of the carboxyl group is replaced by a hydrocarbon branch

Regardless, all information I have seen as well as in discussions with the folks at Redline are that an ester motor oil like Redline will not have problems when mixed with conventional or other synthetic (Group III or PAO) motor oil. There is a general compatability for at least the esters used in motor oil formulations. And I have heard that esters are used in more and more conventional and synthetic motor oils for their good solubility.

Paul, you do realize your web site is the class notes of a 2nd year organic chemistry student? He / she may not be the brightest bulb in the class chandelier. Take what you find there with more than one grain of salt!

I agree that there will be no problem with the two basestocks (ester and hydrocarbon) being able to mix together. I seriously doubt Redline have ever tested the effect of mixing the two basestocks on additive performance. Running a cycle of lab bench tests and full scale engine tests is no trivial matter. In essence, you and others like you mixing things together are doing uncontrolled testing for them. Unfortunately, until there are a very large number of people doing this and reporting results, it will be impossible to know if there are problems with mixing the two oils together or not.

I am only trying to tell you that you have wandered into unknown territitory, and you may find either dangerous creatures lurking there, or less likely you will find the fountain of youth for your automobile engine. I doubt it will be the latter since if mixing some ester into an engine oil formulation was a remotely cost effective performance enhancer, it would have been done already by all the major lubricant manufacturers. The only time it has seemed to make sense to add any ester is for additive solubility, not for performance reasons.

Since your other oils are already formulated to hold the additives, I doubt you are seeing any benefit from adding Redline to the hydrocarbon oils. You may not see any harm either, except to your pocketbook. It may be a small price to pay to exercise your oil hobby ....

I don't see that it is a student. Could it not as well be the professor. But true we should be careful what we find on the net. I found a site that actually says esters are hydrocarbons. I think the problem is that (I have since learned from an article at the fine site of NORIA) while ester is not classified as a hydrocarbon lubricant. However, it does include hydrocarbons.

Mixing ester into hydrocarbon motor oil is probably technically effective, but not cost effective in that the consumer will not buy it (e.g. Castrol Start Up). I believe there are engine oil aftermarket additives (reputable ones) that include ester.

[QUOTE} Since your other oils are already formulated to hold the additives, I doubt you are seeing any benefit from adding Redline to the hydrocarbon oils. You may not see any harm either, except to your pocketbook. It may be a small price to pay to exercise your oil hobby ....[/QUOTE] Yes and without controled experiments we will really never know, but some of us just can't stand to let well enough alone:

What was source of GC compex ester?

M1 may have moved away from esters due to surface conflict, however the views of Silkolene chemist and the fact that esters are used in F1 engines, as they need the highest fluidity, lowest friction resistance, high wear protection, maximum shear stability and heat tolerance, only supports the fact that esters are only beneficial but expensive for road oils.

Magnatec advertise the polar abilities of ester on start up, is this hype, or do esters help during start up period before heat activated aw additives. Are the esters used in Magnatec similar to German Castrol? as they have been decribed as having similar polar attraction as mineral oil.

There is also a conflict between Zinc and moly if not used in balance, however overbasing with both by adding Redline would not appear to be an issue and appears to work with M1 with a dash of Redline.

quote:

Originally posted by MGBV8:
M1 may have moved away from esters due to surface conflict, however the views of Silkolene chemist and the fact that esters are used in F1 engines, as they need the highest fluidity, lowest friction resistance, high wear protection, maximum shear stability and heat tolerance, only supports the fact that esters are only beneficial but expensive for road oils.

The F1 ester oils are fully formulated for using ester basestocks. Not the same as adding ester to an oil formulated to use mineral oil basestocks. Race engines do not have frequent startup issues (see below) and are only operated over a relatively limited range of conditions, albeit high rpm and high heat where esters will work very well. Passenger car engines are not operated in the same manner, and you should not expect the benefits of esters to translate.

quote:

Magnatec advertise the polar abilities of ester on start up, is this hype, or do esters help during start up period before heat activated aw additives. Are the esters used in Magnatec similar to German Castrol? as they have been decribed as having similar polar attraction as mineral oil.

Startup is a completely different lubricarion mode than a running engine. Esters are very poor in EHD lubrication (startup conditions) due to their poor pressure viscosity coefficients. Mineral oils with low VI will do a much better job of maintaining a film in EHD conditons than ester or other high VI lubricants because the mechanical pressure generated by the two metal surfaces will thicken the low VI / high PVI mineral oil more than the high VI / low PVI synthetics. The polarity of the ester and attraction to the metal surface will help maintain the film, but in my opinion the ester will be sqeezed out more readily than mineral oil since the attractive force is only one molecular layer thick. Once the surfaces speed up and reach hydrodynamic conditions, the ester and mineral oil both will be able to keep the two metal surfaces apart based on the viscosity of the lubricant. This is why esters in a rolling element bearing are a potential disaster waiting to happen.

The performance of esters can't be beaten in a high temperature, high oxidation environment (F1 racing engines or jet turbines for example). I just don't believe you take advantage of their properties in normal passenger car engine applications. I also think you may change the way the antiwear additive system performs if you change the polarity / solvency of the base mineral oil by adding ester, because of the attraction of the ester to the same surface the additives are trying to get to. If the metal surface has ester on it when the load comes crashing in and the surface heats up, I want the phosporous or moly there rather than the ester. Like everyone else, I don't have any hard data, just an opinion and my experience with mineral oils and esters in compressors.

When a layer of Electrosyntec molecules is in place, another layer will be attracted to the outer positively charged ends of the first layer of molecules and then another to the exposed negatively charged ends of the second layer and so on, This is electrostatic adhesion and it has been shown that these layers do exist, and that anything from 10 to 50 layers can build up on a metal surface. This is enough to be significant where lubrication is concerned; on finely-finished machined surfaces, the layer can be of similar depth to the surface roughness: i.e. 0.1 to 1 micron (I micron = one thousandth of a millimetre).

The known fact is that esters are expensive and the benfits are only cost effective in high power applications. Intersting that that GC is using I assume a cheap to produce ester for Synth oil.

My own conclusion is that minerals do not need esters, so interested in TallPaul's use of Redline.

Going back to the earlier debate on whether esters are hydrocarbons, Lubes 'N" Greases magazine (Feb 06, Vol 12, Issue 2) on page 18 states:

quote:

...esters have a hydrocarbon structure, plus they have the added presence of oxygen atoms.

So maybe the best way to put it is that esters are a synthesized oxygenated hydrocarbon. Nonetheless, having a hydrocarbon structure, they should be compatible with conventional hydrocarbon oils.