The Life of Oil

[Tom F&L GoR]

This is information from the February 2008 issue of Lubes-n-Greases magazine. The article was an overview of OEM's opinions of oil drain intervals. The graph below was contributed by GM. I'm passing it on because it puts a few things in perspective. It is not meant to determine the actual best number of miles or type of oil.

First, notice how short trips cut oil life to 1/3 that of the longest life. In fact, you're better off towing trailers than driving only short trips. And on an actual short trip there is a load on the engine to help warm-up - this should point out to the folks that start and idle the engine for 10 minutes a week over the winter that you're better off leaving it alone.

Second, notice that the "engine temperature" for best oil life is over 200F. Maybe the 170F thermostat crowd might take notice? Further, if you take this as the oil temp, then it takes even longer than you realize to warm up to this level.

Last, it shows that GM expects their Oil Life System to project an average of 6000 mile drain intervals, longer than the 4800 statistical average recorded at oil change stores. I know I said no numbers, but it shows that GM expects oil drain intervals to be longer than consumers currently change at. They are expecting this system to be a financial, ecological, and energy savings. Unfortunately and dangerously for DIY types, the article says 40% of used oil is still dumped on the ground or in the sewer. Keep this up and oil will not be sold to the public forever.

In the past I have proposed that oil change intervals be based on the amount of fuel used; perhaps change the oil every 300 gallons. Now I propose to you who want to maximize the life of the engine to install an oil temperature gauge and realize that everything is "best" when the oil is not too cold, not too hot, but just right.

 

[Blue Pilot]

Tom, does this study account for synthetic, synthetic blend, and or standard oil? I would think there would be a difference based on oil types.
Good info never the less.

 

[dave6666]

Every 3000 miles for me. Cold or hot. 170 or 180 stat. Highway or neighborhood.

C'mon now, do you think people that drive 10 mpg cars worry about preserving oil by minimizing change frequency?

I do however, like a nice bell shaped curve with my Sunday coffee...

Seriously though, very good comments about the oil temperature business. Too many winter hibernators go out and start their car and consider it to be "warmed up." As you've pointed out many times Tom, all you're doing is swishing the condensate around.

I think I'll carry a copy of that chart with me to show the traffic officer that I was just getting my oil up to maximum life temperature.

 

[ryan94rt10]

thanks tom, for the info...once again you show us helpful hints with our oil!

 

[RACR77]

Great info, thanks for posting.

 

[RTTTTed]

It's not relevant to the Viper, as our cars carry between 9 & 11 quarts in the pan and oil changes are recommended every 6 months.

Prostreeters and race cars benenfited from deep sump oil pans because there was more oil for the engine, the pan was hanging down into the undercar airflow resulting in lower oil temps. Not only was more oil required for perf./race engines, but the cooler oil temps allowed the oil to last much longer. With more oil in the pan there was room for dirt and contaminents in suppession (less oil changes required).

This chart would be for 'normal' 4 quart capacity systems.

Oil temps make a huge difference to the life of the oil. Lower temps allow condensation to stay in suspension decreasing oil and engine life. Higher temps cause the oil to break down and lose it's lubricating qualities.

It only takes 1 overheat for the engine and the oil becomes seriously compromised and needs changing. Too many 'short trips' and the oil needs changing because with 11 quarts it takes a loooong time to warm the oil up enough to evaporate the moisture it carries.

Also, most of the engines wear is on start-up and the warm up period. Highway miles are the easiest on both the oil and engine and a highway car can last double the mileage of a 'city' car.

Ted

 

[Burntrubber]

I think this would also help with the type of oil and weight you would want to use.
In ym Ram SRT10 it is a synthetic 0w-40(which is no news to anyone hear)Mobil . The benefits offered are this, Synthetic requires less warm up time to get to its "hot" weight of 40, and since it is a "0" weight when cool it can circulate through the engine quicker and lube the entire engine. Onve it reaches it "40" weight it is at its thickest which means it offers its best protection. Since our V10 generate alot of heat you get virtually no wear on long trips.

 

[Tom F&L GoR]

"Tom, does this study account for synthetic, synthetic blend, and or standard oil? I would think there would be a difference based on oil types."

No it doesn't, since the GM oil monitoring system can't determine what oil you've put in. Therefore they predict life for a very generic oil, meaning the latest API performance level. HOWEVER, I have frequently pointed out that the major benefit to synthetics is rarely needed. Extremely low temperature pumpability (at temperatures you wouldn't go out in anyway) and at very high temperatures (when all the gaskets have hardened and seals have melted.) It's the additives that do the work. Look at Euro oils, or in the US look at diesel oils - they are designed for far, far longer and have 2X the additives that US passenger car oils do. Anyway, that's another thread.

As to how relevant this is... even if the chart is for "normal" systems of 4 quarts, engines are "normally" 3L in size. So if an 8L engine has 9-11L, it's still at the same ratio of engine size to oil capacity. And that recommendation of 6months - the chart is coming from an OEM that makes those kinds of recommendations. I would learn from this, not dismiss it.

All those deep sump pans were a bandaid for not having dry sumps, if you ask me. They gave the oil a place to go and get picked up by the oil pump under massive acceleration. F1 engines, at their 20,000 RPM and 930 HP peak from a "normal" 3L, still only carried 4-5L because they managed it well.

"With more oil in the pan there was room for dirt and contaminents in suppession (less oil changes required)."

I think you meant "in suspension."

Lastly, SAE pumpability studies show that wear on start up is insignificant as it pertains to the life of the engine. In fact, that is how the "W" number came to be - and so any oil (whether synthetic or not) such as 5W-30, a 5W-40, a 5W50 all have met the same criteria for cold starts. If you start your engine within the temperature range the oil was designed for, you won't experience engine life decrease.

On the high temperature end you will decrease the life because you use up the anti-oxidant protection and it thickens. However, it is better predicted by saying that the life is halved for every 10 degrees above 270F you operate. Another reason for that gauge...

 

[black mamba1]

I think the major benefit the synthetics offer is significant. Regular oils are comprised of a carrier (the basic hydrocarbon base) and additives (which fight moisture, etc). The problem in regular oil is that the base is hydrocarbons. And hydrocarbons have a natural affinity for H2O. The chemical bonds in hydrocarbons are less than a third as strong as those in polyalaolefins (a mobil one synthetic carrier) and therefore break down easier under hydro attack. The much stronger chemical bonds in Mobil One result in the carrier maintaining its initial characteristics over a longer period of time and over wider temperature ranges due to less breakdown.

Regular oils are fine for Honda Accords being driven to the supermarket, but for engines routinely revving to 6000 rpm in Florida heat and humidity? I would only go w/ synthetic.

 

[RTTTTed]

And by 'synthetic' you are including Group 3 oils? Since it's OK for Group 3 oils to be advertised as 'synthetic' how would you be able to tell the difference?

Just use Mobil 1 and you're good to go. lol

Ted

 

[Burntrubber]

Only Mobil 1 for my snake

 

[Tom F&L GoR]

I think the major benefit the synthetics offer is significant. Regular oils are comprised of a carrier (the basic hydrocarbon base) and additives (which fight moisture, etc). The problem in regular oil is that the base is hydrocarbons. And hydrocarbons have a natural affinity for H2O. The chemical bonds in hydrocarbons are less than a third as strong as those in polyalaolefins (a mobil one synthetic carrier) and therefore break down easier under hydro attack. The much stronger chemical bonds in Mobil One result in the carrier maintaining its initial characteristics over a longer period of time and over wider temperature ranges due to less breakdown.

Regular oils are fine for Honda Accords being driven to the supermarket, but for engines routinely revving to 6000 rpm in Florida heat and humidity? I would only go w/ synthetic.

Uh, no. Oil and water don't mix. If you think you see they do, it is the additives. Additives are three parts - the active end (detergency, dispersancy, wear protection), the soluble end (so that the additive dissolves in the oil) and the body (that which connects the active and the tail sections.) Water plays havoc with any additive because it interferes with the activity portion. This happens in synthetic or mineral oil.

Regarding the Group III question. "Mineral oils" are a bell curve with a big popluation of good stuff in the middle and some smaller and heavier molecules. If you refine the mineral oil even more (minimizing the ends of the bell curve) you get Group III oil. Think of Group III as twins, triplets, etc. since they are mostly identical. It performs identically to synthetic (except for ultimately freezing at -50C) and even oil company labs will have a difficult time showing a performance difference (reference the Mobil vs. Castrol fight, which because the industry standards could not tell the difference, Castrol was allowed to call Group III a synthetic oil.) To finish the story, a synthetic base oil is "made" by stitching together small molecules to make exactly the size molecule you want. Think of it as a bunch of clones.

I personally have no problem with calling Group III a synthetic except that it is 2/3 the price and Castrol still charges you full prices.

Yes, the widest range viscosity is best all around with no debit. An SAE 0W-40 is an excellent formulation, and it carries Euro specs (more additives).

 

[Catwood]

so am I wasting money by changine my oil every 300 to 500 miles. this assumes a couple of track days and the time inbetween. I usually change before an event. Is it cheap insurance or am I throwing good money away?

 

[Performance Junkie]

Good information.
I was shocked when I got my wife a BMW Z4 3.0 they wanted oil changes (real synthetic) and 15,000 mile oil changes. The computer let you know by observing your driving habits to change earlier if needed. We had to at 12,000 but still its amazing.

 

[PacificSEASnake]

so am I wasting money by changine my oil every 300 to 500 miles. this assumes a couple of track days and the time inbetween. I usually change before an event. Is it cheap insurance or am I throwing good money away?

Every three hundred miles? Is your Viper on dialysis?

 

[Ron]

Thanks Tom, always enlighting.

I took Tom's advice and went diesel but I couldn't get over the psycological hurdle of a non-synthetic in my Viper and went for Mobil's Delvac 1, the "Mobil 1" for diesels at a 5W-40 weight. I do let it stay in the pan for 2 seasons and over that time it hits about 2k miles with no winter warms ups.

Proof of plan is great used oil analysis every time.

 

[Catwood]

Every three hundred miles? Is your Viper on dialysis?

I change between track weekends typically. As I write the mileage on the filter I'm always surprised how little the cars driven between those events.

 

[Tom F&L GoR]

Catwood, for the price of all that oil you should spring for a used oil analysis. That will tell you how much you "use up" the oil at a track event.

My guess is that a fuel injected engine doesn't dilute the oil with much fuel. Your engine is in good shape, so there is no excessive blowby pushing acids into the oil. You don't overrev the engine, so bearing wear is normal. You have roller lifters so cam wear is minimal. You might get ring/liner wear because of the higher combustion pressures and you probably have higher oil temperatures. (Got an oil temp gauge?)

I think the wear protection is good for more than a few weekends and if you are using a top quality oil or synthetic, I don't think it is degrading - does it come out dark? You aren't using a race-only oil, are you? They often don't have detergents and dispersants. We'd all be very interested in what the oil shows after a weekend.

 

[Catwood]

I use only Mobil 1. It is darker after a full weekend but if it's a day event it looks nearly like new. It's never as dark as one of my other cars which run mobil 1 also. I used to reuse it in a ****** but that gone now.

Where do I go for an analysis?

 

[Steve 00RT/10]

I have put as many as 10,000 miles (many road trip miles), with 2 hard track events and a couple autocrosses, on my 0W-30 Amsoil........and the analysis comes back good to go every time. Typical change is 5000-6000 miles with one track event somewhere in there and an autocross or two. I have done oil analysis since new. There is now 75K miles on the car. It uses virtually no oil if mostly highway driving. Changing oil may be cheap insurance as many say, but it seems a waste of money if driving under normal conditions with a good oil in the crankcase.

Steve

 

[ontilt]

Re:Oil analysis

I have used blackstone labs (blackstone-labs.com) many times for my diesel truck. I used to change all my vehicle's oil every 3-5 K miles. After doing several oil tests I concluded that the oil companies are getting rich by us following the "eyery 3000 MI rule". I now change my truck oil every 7-10 K miles. Even at that the oil tests fine.

 

[Steve-Indy]

...and Blackstone Labs has a fairly large experience with Vipers !!

 

[whitebluevipe]

Tom,
in the winter is it better to start the car and let it run every so often or is it better to leave it sit all winter without starting it? tia

 

[Tom F&L GoR]

Much better to let it sit. Over one winter the oil, fuel, and other fluids will be fine. The colder, the better. Everyone knows better, but for the sake of completeness, always use a multigrade oil.

 

[kcobean]

I moved this to General Discussion just because this is awesome info for Gen-3 owners too.

 

[snakebitdave]

Great info; thanks. I'm hoping you could give me some additonal advice for my cars. Some of you would consider my cars to be "garage queens" in that none are driven more than 2,000 miles per year and stored in a climate controled garage. When they are driven they are thoroughly warmed up. Each has Mobile 1 oil. Is there a "shelf life" so to speak? How often should I change my oil under these conditions?

 

[Kenneth Krieger]

Had an oil analysis done on my previous diesel truck after 15K with no oil change. Came back good.......went another 5K and STILL came back good.....but, became a little nervous and just thought it was time to change. That was Rotella........I assume Mobil 1 would probably do the same, but.....I still won't go more than 5K between oil changes in any of my cars.

 

[ontilt]

IMO: If my diesel PU that has 160,000 mi on the ODO, tows and is driven hard can have a clean oil anayisys after 7-10K miles on reg oil, I cant imagine that a garage queen viper or even a normal driven one can need the oil (esp synthetic) changed any more than every 5-10 K miles.
I would bet that a normal Viper could get away with NEVER changing the oil in its life. I have friends that have run the same oil in trucks 100K miles and more with only filter changes.
I admit though that I along with others have a "thing" with changing oil at those intervals. For years I have always changed my vehicle oil every 3000 mi, not anymore its a waste!!!. I go 7-10 K in all my cars.

 

[Steve 00RT/10]

I haven't followed the 3000 mile rule since the mid 70s. I probably have close to a million miles using synthetics and extended drain intervals with a filter change in the middle. Granted, much of these miles were highway miles to and from work....but I was going 20k miles between changes with analysis on about half of those miles. I have never had an internal engine problem on any vehicle. The synthetic oil which was in the last Viper we bought a couple years ago had not been changed in 2.5 years and 6000 miles. It tested out just fine. The 2001 5.3L 4x4 pick up I have now has 142,000 miles on it (all mine) and the oil was changed every 20,000 miles -- with analysis -- up to 123,000. It no longer runs the road. Since late 2003, I change the oil once a year and about 4-5000 miles....mostly short trips. It uses about 3/4 qt over the time frame. I've had zero engine issues. I don't even bother to analyze these 'short' drain periods with the truck. I just sold a 1990 SHO with 160K miles which was on Putnam Park a couple years ago in 100+ degree heat all day long. As anyone whose been there knows....there ain't no shade at all. I ran 6 sessions there that day and parked it in the hot sun between times. Absolutely never had an engine issue with that car.....but then 160K miles on a SHO isn't much. There was a like car there with 450K miles on the odometer and he didn't miss a beat either. I hope our Vipers hold up as well.

Steve

 

[black mamba1]

Uh, no. Oil and water don't mix. If you think you see they do, it is the additives. Additives are three parts - the active end (detergency, dispersancy, wear protection), the soluble end (so that the additive dissolves in the oil) and the body (that which connects the active and the tail sections.) Water plays havoc with any additive because it interferes with the activity portion. This happens in synthetic or mineral oil.

Regarding the Group III question. "Mineral oils" are a bell curve with a big popluation of good stuff in the middle and some smaller and heavier molecules. If you refine the mineral oil even more (minimizing the ends of the bell curve) you get Group III oil. Think of Group III as twins, triplets, etc. since they are mostly identical. It performs identically to synthetic (except for ultimately freezing at -50C) and even oil company labs will have a difficult time showing a performance difference (reference the Mobil vs. Castrol fight, which because the industry standards could not tell the difference, Castrol was allowed to call Group III a synthetic oil.) To finish the story, a synthetic base oil is "made" by stitching together small molecules to make exactly the size molecule you want. Think of it as a bunch of clones.

I personally have no problem with calling Group III a synthetic except that it is 2/3 the price and Castrol still charges you full prices.

Yes, the widest range viscosity is best all around with no debit. An SAE 0W-40 is an excellent formulation, and it carries Euro specs (more additives).

No no....one Tribologist to another, I did not say oil and water mix, I simply said that hydrocarbons have a natural affinity (polar chemical attraction) to water. The number one problem w/ most oils is oxidation (reactions w/ water) and breakdowns b/c of. Carbohydrogens will always naturally react w/ water, and all natural base oils carry a carbohydrogens. My view is that polyaleolefins (Mobil one synthetic base) simply do not have nearly the vulnerability to oxidation as natural (carbohydrogen) oils, having chemical bonds much stronger and that hold up to higher temps and oxidation attack far superior to paraffin oils.

Paraffin oils (natural oils) must add additives to even begin to approach the viscosity hold up and performance temperature range of a polyaleolefin and as those additives wear and break down, the entire base oil characteristics drop off. I am sure there are some really good additives out there, but I would rather have a robust base oil (carrier) as well as good additives. And that for me is Mobil 1.