Group I better than Group IV??

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sweetning the bulk oil with various esters would be the easist way to clean the machinery while in use. I do not recall ever haveing an issue on a vechile that has been run it's whole life of GIII,GIV or GV oils. Even with GI and GII oils if the OCI was not excessive and the emission system is working properly varnish was rare. Varnish is normaly an indicator of poor maintnece,defective fuel injection system, emission system or wrong oil for application.
 
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All of my customers for turbine oils are on group II, and none have ever commented on varnish.
This post should be deferred until Ron AKA starts his "Group II better than Group IV??" topic....
 
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Ok first off varnish is a precuser to sludge and will affect heat flow to/from bearings. GP1 oils have better solubility to varnish and sludge BUT they are also not near as good for oxidation resisitance. A Inhibited GP1 turbine oil tested in ASTM D 943 will be about say 2,000-2500 hours to a 2 TAN a GPII that is inhibited is 9,000 hours or so. So a GPII will last much longer BEFORE it will start to form varnish and sludge BUT it will. So using FTIR ot at least a routine TAN MAY tell when to change the oil before any problems start. No matter the quality of oil if it is ysed to long before change out sludge and varish will form. Also a routine perhaps every 1,000 hours testing will show things like debris, water, solvents even cross contamination from other oils etc. So IMHO a GPII changed out at say 8,000 hours will product less varnish and sludge than a GPI changed out at 2,000 hours. Also oil vedors quality leveals are all over a dispersant additized oil with the correct AO package in a GPII will be the best if monitored and not run to death. Chevron has a real good one for turbine use with good AO and solvency forgot name but check with them. As far as system cleaning a GPI will not do to well normally a high aromatic oil is used to flush systems these are like the oposite of a parrifinic oil will low aniline pt and high solvency mobil called there version Mobil sol with aniline points of about 120F. bruce
 
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120 F as in frank high flash and good solubility. do not know if Mobil or other majors still supply aromatic oil tho. bruce
 

Ron AKA

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First off: Turbines run on Grp II oils? Is this correct? I thought turbine applications required Grp IV or V anyway.
It depends on the type of turbine. Steam driven turbines that are 10-15 years or older probably started out on Group I oils. Gas turbines that are frame type may use the same oil depending on vintage. Aeroderivitive gas turbines most likely use very special synthetic fluids (IV or V) that have to be explicitly qualified by the mfg. This is probably a good thing as these are the type you find under the wings of planes you fly on. The problem of varnish is primarily a problem in the frame gas turbines and to a lesser degree in the steam turbines. The turbine I gave an example of has a minimum spec for VI of 90. A group I should meet that easily. The problem has actually come about when owners put in Group II, or the vendor of the group I changes it to a Group II without the owner/purchaser knowing.
 

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[quote}So IMHO a GPII changed out at say 8,000 hours will product less varnish and sludge than a GPI changed out at 2,000 hours.
Bruce you make some good suggestions and I will have to take some time to review and digest them all. One point that may come as a surprise to some is that normally the oil you put in your turbine new is the same oil that is in the machine 30-50 years later (less some leakage loss and replacement). It is consididered a failure of the maintenance system to have to change out a batch of oil. Considering that a system can have in the order of 5,000 gallons there is a good reason to avoid doing that. So turbine guys may be the ultimate extended oil change interval freaks! So that is where all the concern has come from. These newer machines that are just getting to 10 years or so and having varnish problems are failing 20-40 years too soon. The primary conclusion seems to be that newer machines have Group II oil instead of Group I, and that is leading to the varnish.
 

Ron AKA

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sweetning the bulk oil with various esters would be the easist way to clean the machinery while in use.
Could one expect an oil supplier to do this? or would they be more inclined to just try and sell you a new batch of oil, citing liability reasons etc....
 
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It depends on the type of turbine. Steam driven turbines that are 10-15 years or older probably started out on Group I oils. Gas turbines that are frame type may use the same oil depending on vintage. Aeroderivitive gas turbines most likely use very special synthetic fluids (IV or V) that have to be explicitly qualified by the mfg. This is probably a good thing as these are the type you find under the wings of planes you fly on.
In your first post you mentioned "fleet". For some reason that translated to "ship" in my head . I was thinking of turbine drive engines which are indeed aircraft derived and would require a much better oil than a Grp II. After re-reading your first post, you in-fact did not spec. what type of turbines you are talking about.
 
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Ron more thoughts, In a on line OLD system using GPI with good bypass filtration (running at close to staturated "sludge" leval) I think over time or with a partial change to GPII the new oil will rasie the aniline point and knock out varnish and sludge. Otherwise as in a IC engine ANY oil run past its usefull life will varnish and sludge up. bruce So of a change is made to a "better" GPII oil the whole system should be chnaged out or a outside "filteration" company comes in a runs a full 100% cleaning of the whole system.
 
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I was under the impression this section was for "Car and Truck Gas Engine Oil", not stationary turbine oil.
If I were to use group I in my saab, it'd probably become stationary pretty quickly. Does that count?
 
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