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Discussion Starter #1
What is your guys opinion of using Synthetic Fluids throughout my truck. Gear oil, tranny fluid, diffs, and engine? I have a 85 Chevy Blazer with a Turbo 400, 208 Transfer case, and ten bolt diffs, with the gov lock in the rear. Of course I have a 6.2 diesel. Thanks!

Guipo
 

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Synthetic engine oil

Check your engine manual because it will indicate that you should use a 30 wt. CD oil except for short trips in the winter. I use Delo 400 30 wt. year round. Those engine bearings need a high viscosity oil. Don't ruin your engine with the thin watery stuff.
 

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When the 6.2 came out there were not any 15/40 diesel oils to be found and 30 wt was the preferred oil. In the later years of production on the 6.2 15/40 was the specified oil. Main concern is the oil rating. Minimum of CD rating for a 6.2. Most of the current diesel oils are CH or higher. I have run Mobil 1 10w30 for winter use without any problems, it provides fast cranking in cold weather, but change it when it is dirty, because the oil will soot up and soot causes wear. Mobil 1 is only rated CD so it is on the low end of Diesel sythetics. Shell makes rotella 5w40 synthetic and it is carried a most walmarts for 12+ a gallon. 6.2's and 6.5's all share same bearing dimensions and are interchangable. Whatever oil you use in a 6.2 synthetic or not I would not go over 6000 miles max between changes. Some years back Laidlaw and Mobil 1 combined to see if by using synthetic oil in their 6.5 TD school busses they could extend oil change intervals. They ran their oil for 10,000 miles and ruined a lot of engines.
 

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Ahh, the choices are many and varied! Opinions also vary. I don't doubt anyone's experiences and when asked to debate the subject, usually say, "To each, his own". If you follow the manufacturers recommendation on the oil spec and weight, you will be ok.

Back when your owners manual and your visor instruction sheet was printed, the factory was new to the production of light duty diesels and was doing their homework. They recommended H.D. (CD rated) 30wt because they knew it would provide adequate protection.
 

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Discussion Starter #6
cool

Cool, Thanks for all the info. I was thinking of using mobile delvac 1, or rotella synthetic. Its pretty thick stuff, 15-40 I think. I've always used 15-40 in my blazer.

Is Synthetic ok in the rest of the drivetrain, tranny, differentials and stuff? I have a rear locker(gov-loc). Does that need the special additive that limited slips need?
 

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Synthetic is awesome in rear axles especially with a limited slip or gov loc. No additional additives are required with most oils that I have run and with standard clutch type posi's the synthetic takes away almost all of the chatter including some of the front powerlocks I have used in jeeps. Oils that have worked very well include Redline, Royal purple, and Mobil 1. I prefer the 80/140 weight for the added shock cushion and for towing.;)
 

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Synthetic is better but more expensive. Either way metal wears and fluid gets dirty. Best to change them frequently no matter which kind of fluid you choose to run.
 

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6.2L engine oil

D.Camilleri: This is what my 1984 pickup owners manual states for the 6.2L engine:

SAE 30 viscosity oil is preferred and should be used whenever possible.
(SAE 30 is also preferred for continuous duty driving). Use SAE 10W-30 or
SAE 15W-40 for cold weather operation when you expect the temperature
to repeadly go below freezing (0C, 32F) before the next oil change.

DO NOT USE SAE 10W-40 or any other viscosity oil not recommended. such oils could cause engine damage, and such damage is not covered by the new vehicle warranty.
____________________________________________________________________

I have always used the 30 wt. CD type oil from day one in my engine. I have always had to carry Delo 30 wt. CD oil with us for oil changes on our long trips since all of the oil change shops do not carry the 30 wt. CD oil any more. Sometimes I make two oil changes before we get back home and that can be ahassle, especially in bad weather.

I wrote Chevron about using Delo 15W-40 CD oil in my 6.2L engine due to the lack of availability of 30 wt. on trips and their written reply was that I should Delo 30 wt. CD in my engine!!!

I don't know what else to say when my manual and Chevron say to use the 30 wt. CD oil. Diesel ignition really pounds the bearings, cranks, and cylinder walls so I think the heavier oil film does help.

I know current auto manufacturers recommend 5W-20, but that is because that oil saves fuel. The manufacturer's don't care how long the engine lasts, but they do care about meeting the mileage dictate from the government. I suspect the engines would last a lot longer if 30 wt. CD oil were used!!!! A friend ruined his Mercedes diesel by using Mobil 1 during the 1980's. I used Delo 30 CD in ours and it had over 240K miles on it when I gave it to my daughter.
 

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cougar john,

I respect your opinion and years ago I also ran 30 wt Delo 400, but oils have evolved and newer 6.5td's specify 15w-40 with the oil rating being of the utmost of importance. When the 84 6.2 was made, the highest diesel oil rating was CD with CC also being exceptable. I have rebuilt many 6.2's and 6.5's that were run on various oils and the majority of engine failures were not oil related. For example a friend of mine has an 82 gmc, when it was approaching 300,000 miles on the odometer he asked me," how long is this thing going to run?" I told him probably until something breaks. A month later a wrist pin broke in half and ruined the block. That engine ran it's life starting with 30 wt but finishing with 15-40. It would have still been running had it not suffered a mecanical failure. I have also witnessed engines that used the wrong type of oil (not CD) such as 10-40 that gunked the inside of the engine so bad that it took hours to clean parts that are normally clean. The very first 6.2 powered truck I ever owned is a 1983 gmc that now has over 325,000 miles and is owned by my dad since I sold it to him about 200,000 miles ago. The last 200,000 miles have been with 15-40 delo 400. We could agree to disagree and never reach a verdict, use what you are happy with. I use 15w-40 delo 400 exclusively in my 400 hp cummins and it serves me well. Would I consider something else, you bet, when it gets real cold around here 5w-40 sythetic is much better for getting oil flow to the critical parts of the engine and I just stumbled accross a TSB for the Duramax that specifies the use of 5w-40 when the vehicle is operated at temps below 0 F.
While I haven't ever seen an oil related problem from using a good 15w-40 oil in any driving condition, I have seen major engine failures resulting from using 30 wt oil when it suddenly got cold. These failures include broken oil pump drives and wasted turbo bearings. Oil that doesn't flow doesn't lubericate. I know that when you quote the owners manual, you will say,well you should have been running a thinner oil for those colder tempatures, so here we go again, personal preference. One last note, late model 6.5's specify 15w-40 engine oil, these engines are turboed and have much higher bearing loads and higher overall oil tempatures than NA engines and use the exact same bearing dimensions, clearances and bearings as your good ole 6.2.:cool:
 

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One of the most oft questions asked what oil do I use, matter of choices, new synthetics cost the most & do an excellent job, but as stated earlier oils also have changed, this ain't your grandpas oil no more, while straight dino is available still; dino blends sort of dominate the shelves that come very close to what synthetics do. I like Shell Rotella 15-40W, & DELO 15-40W, but I'm turboed so I put oil to it's paces. Buy oil in quantity and you can save, I get 5 gal of Rotella for around $32 a bucket, pour into 1 gal bottles for convenience.

How often do I change it is another frequent question, that depends which oil you use, your driving style, & health of your engine, general consensus I see on forums is 3500-5000 mile range, using synthetic that gets to be big bucks, synthetics have extended interval might push that into 6-8K. Still at 2 & 3X the prices of dino oil in long run for me dino saves money and I'm still protecting my engine.

Add bypass filtration and you can make dino get into same change interval as synthetic, I'm on 3rd iteration of an experiment I've been running how long can it go. Using oil sample program from lube specialist http://www.lubespecialist.com and others is only way to know for sure if your oil is safe to stay, I sampled at 3500 mi, 6500 mil, and have a sample waiting to go for test with 9000 mi, I changed the oil on that last one just on gut feeling it was time. I'd be willing to guess that the sample will say the same and that optimal time with dino and bypass filtration will be in 7K interval neighborhood.

I guess you could extend synthetic with bypass filtration also but I'd run a sample program to be sure, but don't push it too far to the right, oil change time is also a great time to do the other inspections for broke stuff, & loose bolts, wires, and any other wear & tear thing that needs looking at.
 

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6.2L engine oil

D.Camilleri: Your post comments are all good, but I just hate to violate the owner's manual plus Chevron saying I should use Delo 400 30 wt.!!! The Chevron statement surprised me since Delo 400 15-40 viscosity at 104 deg.F is 15.6 versus 12.1 for Delo 400 30 wt. and at 212 deg.F it is 116 versus 105 for the 30 wt. which looks better to me. And the poor point is better for the 15-40.

I have about 225K miles on my engine. It is about time for an oil change so I may try the Delo 400 15-40 since the weather is still cold to see how the oil pressure is affected. The mech. oil gage still indicates 35 PSI at 55 MPH as it has from when it was new.

Do you or anyone else know what the film pressure is for 15-40 versus 30wt.? The highest film pressure is suppose to be for synthetics, but I can't use that in my engine.
 

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cougar john,

I don't know if you are familiar with the diesel page, but maybe you could send a message to Doc Lee Swanger who was an engineer for clevite and is very knowledgable on this stuff.:cool2:
 

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This is cool! I'm learning as we go. I, too, have preferences and experiences. Some of the failures I've seen have involved the dreaded 10-40w stuff.

That was dynamite in the 5.7s as well.. I rebuilt dozens of them for "using excessive oil" complaints. Much of it was just cleanup of rings and ring lands. Reinstall the same rings and assemble. Flush the engine, pan, pump. etc., change it over to 30w CD and off they went with no more problems.

I have used 30w CD since day one in all my stuff. (Some of which, you don't want to know about) My "babies" (read: junk) are all old, high mileage and ugly. My '64 Dodge Dart slant 6 has 500,270 miles on 30w CD. Yes, it's been apart a couple of times. Things wear out, apparently. My '80 Olds 5.7D has 277,000 (my daily driver, work car, 70 miles round trip) with 30w CD. All the tractors, motorcycles, cars, trucks, and equipment have all run on 30w CD for years. The first to change over was my '66 Triumph Bonneville 650cc road bike. I was in British Columbia in 1968 on a 5 week tour and needed to change oil. Couldn't find Valvoline 40wt anywhere in BC so changed it on the road to Pennzoil 30w CD! Have used it ever since. No oil ralated failures yet.

I buy it in a 55 gal drum. Last price was around $320. I made the decision to change over to 15-40w when I ordered the last barrel. So far, everything is still working. Hope I didn't create a problem some long way down the road. I think from what everyone is saying, I should be safe. I got the same story from the factory reps about, "Don't change the weight/formula, etc." I felt it was time to move into the '80s (or whenever it was that this modern oil stuff started!)

"Stuck in the sixties", Fred
 

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Discussion Starter #15
Mobile Delvac 1

i've heard that Delvac 1 was absolutly the best synthetic oil for diesels. I own a VW Passat Tdi, and its one of the few oils that all those VW snobs agree is really really good. Its supposedly (and take a opinion with a grain of salt) the best. I know a trucking company in my area that lets their big rigs go 15000 miles on one oil change. its 5w-40w too. I use it in my passat and I go 10000 miles on a change.

I mean, if its good in big rigs for 15000 miles, why wouldnt it be good in my 6.2 for 7k.

Buuuuut, I wont use it. 40 dollars for oil every change dosent apply to my cheapness.

SIDE NOTE: They sell the same stuff at stores called Mobile 1 Truck and SUV. Just repackaged. Good stuff.
 

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I run Rotella in my truck, Ford 535 tractor, John Deere 2020 tractor, & wife's VW TDI bug, as you see with this many Diesels to feed; quality dino oil is the ticket for me can't afford that much syn.
 

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Discussion Starter #17
From what I understand with the TDI, and since I own one, VW says you must run a certain certification of synthetic oil in your tdi. One thing I've noticed about VW's, you follow the rules when it come to fluids, or you have things break. I use rotella in my 6.2 though! Love it, cheap, quick and works well.
 

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I maintain a fleet of over 30 vehicles ranging from tractors to 2004 cars, some recommend 5w-30 and others 30wt, well they all get diesel rated 15w40 that also has the high end gasoline rating of SH. I have never had any oil related problems except for our Kawaski mules and I just changed them over to Mobil 1 5w-30 because it is a lot easier on starters and engine cranking speed when it is -20f. As far as oil change intervals, I seldomly follow manufactures recommendations, I usually change much sooner, most vehicles at 3000, tractors at 50 to 100 hrs and vehicles that see only short trips at 2000 miles. Most of us forget that there is also a time interval specified in our owners manuals and most recommend oil change at 3 months regardless of mileage. This is due to the fact that short trips cause a build up of condenseation in the oil. For my money, the only time sythetic really makes good sense in an engine is when you drive lots of miles and want to extend you oil change intervals so you don't have to change it every other weekend, or in super harsh envirements like winters in Wyoming where dino oil doesn't flow very well.:cool:
 

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Me too! 2000 mile intervals on most of my stuff ( I have 10 vehicles registered and insured for the road plus 3 tractors). The tractors and equipment at 50 hrs. The small engines that only hold one quart, no more than 8 hrs. As I said, it's all old junk! I figure a barrel of oil is cheaper than an engine. I'm more concerned about the time loss when fixing them then the parts cost. (I have lots of used parts)

At work, I maintain a fleet of 130+ vehicles for a large utility and everything gets 15-40wt.
 

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Diesel Page forum

D. Camilleri: I use to be a member of the Diesel Page forum (about 4 years ago). I checked back last year and it seemed that it was mostly DuraMax now. Maybe I will check back because it use to be a good forum and the cost was low.
 
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