longer oci's

[LarryL]

I looked through a fleet operations database (that uses software I wrote) at sedans that average 25k a year and get their oil and filter changes twice a year with synthetic oil. These vehicles are driven by the same drivers and are well maintained, but see a lot of stop and go driving. The brands vary between Honda, Toyota with a few Fords and Chevys. Another branch of the fleet does 3-5k changes with conventional oil and, generally, they all make it to 100k miles/4 years with few if any problems. Threre is one difference though. If a car needs repairs, the longer oci cars require more labor, parts and suffer more down time if the repairs come late in the third year or the forth year. This averages out over 100+ vehicles in the long oci fleet and 200+ in the conventional fleet. Repairs done in the first two years or under 50-60k miles follow very similar patterns for both groups. The data I looked at was for 1/1/2002 to 10/28/2004. If a car in the longer oci fleet did not require any unscheduled repairs it would do just fine right up to 100k, just like the short oci fleet cars. I would like to tear down a car from each fleet at 100k miles but the owners are just not interested, they are playing golf. They tell me to keep working on the software, that their fleets are ok. The synthetic oil is Mobil 1 and the conventional oil is Chevron Supreme. They are in the process of switching over to all Chevron products, starting Oct 1st this yeaer, and so far a group of 10 Hondas are running on Chevron Supreme synthetic 5w-20 with no problems. These are not included because they are short on the mileage and time and were picked because they see almost double the mileage per year (yikes).

When calculating the numbers, so far, it's cheaper to do longer oci's on average. That takes in cost to do the oil changes, down time for oil changes and the few cars that will need extra time and money in the future. I'm just wondering if anyone has any comments.

 

[oilyriser]

Are they doing any UOA's?

 

[MIAMI-DADE]

quote:

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. I would like to tear down a car from each fleet at 100k miles but the owners are just not interested, they are playing golf. They tell me to keep working on the software, that their fleets are ok. [/QB]

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I think their 2 busy playing golf and getting sun poisning to be bothered with UOA's.

 

[LarryL]

At times they will pick out a couple of vehicles and track them, but if they have a bunch of vehicles used about the same way, they let the mechanics doing the maintenance choose when to do one, and that's not very often. They did choose to change oil suppliers and both performance and cost of oil were factored in but it will take a year or so to see if what happens. I've asked if they would let me post uoa's but they said no. They spend a lot of money doing maintenance and tracking it and we have a lot of failure data but they say is only available for a price. I have talked in general terms about experience with oil changes and that's ok, but a uoa is out.

 

[Gary Allan]

What's the difference in costs of non-maintenance repairs (did I miss it) ..I mean is it THAT much different? 150% ..130% 200% ..and what is the retirement requirement for a unit?

 

[KW]

I wonder why the longer OCI vehicles require more down time and parts for repairs the the shorter OCI vehicles when they did break down?

 

[LarryL]

Vehicles go 4 years/100k miles. The greater majority of vehicle have no problems at all. Repair bills as explained run higher, about 50% and average downtime is a little more than doubled, from a little over one day to almost three days for the longer oci vehicles running synthetic. Maybe the bigger difference between synetic oil and conventional oil is the ability of synthetic to go longer between changes than its actual lubrication performance in normal driving.

 

[vad]

quote:

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Originally posted by LarryL:
There is one difference though. If a car needs repairs, the longer oci cars require more labor, parts and suffer more down time if the repairs come late in the third year or the forth year.

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Are those engine repairs only?
If not then the data is largely irrelevant and has no correlation to the length of oil change intervals.

 

[farrarfan1]

quote:

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Originally posted by LarryL:
Maybe the bigger difference between synetic oil and conventional oil is the ability of synthetic to go longer between changes than its actual lubrication performance in normal driving.

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That's the question I've always wished someone could answer.Does a synthetic like Mobil 1 actually lubricate better than a good dino?

I've searched throught he archives here and have never found a definitive answer.

 

[LarryL]

quote:

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Are those engine repairs only?
If not then the data is largely irrelevant and has no correlation to the length of oil change intervals.

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The subject is oci's and engine oil, the two main variables, no brakes, transmissions or electrical systems. Where did I get you get side tracked?

 

[vad]

quote:

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Originally posted by LarryL:
I looked through a fleet operations database (that uses software I wrote) at sedans that average 25k a year and get their oil and filter changes twice a year with synthetic oil. These vehicles are driven by the same drivers and are well maintained, but see a lot of stop and go driving. The brands vary between Honda, Toyota with a few Fords and Chevys. Another branch of the fleet does 3-5k changes with conventional oil and, generally, they all make it to 100k miles/4 years with few if any problems.

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The group that uses synthetic with long intervals sees a lot of stop-n-go driving.
You don't give us any info about the driving conditions of the other group that uses dino.
You're tracking the repairs. O.K.
If the cars in the dino group are not operated under the same conditions, e.g. don't experinece a lot stop-n-go traffic, don't you think that they would develop far less problems due to the more favorable driving conditions?
You're making observations based on some who knows what data and then asking for comments without giving us the complete picture.

 

[vad]

seeing double

 

[XS650]

quote:

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Originally posted by LarryL:

quote:

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Are those engine repairs only?
If not then the data is largely irrelevant and has no correlation to the length of oil change intervals.

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The subject is oci's and engine oil, the two main variables, no brakes, transmissions or electrical systems. Where did I get you get side tracked?

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Larry, I appreciate you posting the results of your study here and am looking forward to more information, but I don't believe he was side tracked. I don't believe you stated that your data only included the engines.

Readers would be remiss to assume you meant that something you didn't say directly.

 

[slickfisher]

quote:

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Originally posted by vad:
seeing double

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Me too. Feel like I'm at a bean counter seminar.
I really like Chevron's synthetics though.

 

[LarryL]

All vehicles drawn out saw the same service. There were others that were not included because they did not fit the group. The only difference was the oil type and oci. I'm trying to get premission to publish the data with specifics and examples. I did not mean to infer that the longer oci vehicles saw different services. If they did there would be nothing to compare. And the difference in repairs only showed up in the second half of the four year cycles. If the vehicle did not need unscheduled maintenance there was no difference in expenses other than the time and material to do the oil changes.

Amoung the maintenance managers they switched the synthetic oil to Chevron and the conventional oil was always Chevron.

 

[XS650]

Larry, could you give us a generic rundown of the types of problems that are seen in the higher mileage cars and any specific differences you have noticed in addition to repair cost.

 

[Tones]

My guess would be that the shorter OCI cars are in the garage more often and thus get more attention than the longer OCI cars. Things like engine oil level, coolant level, filters, etc. are addressed sooner before they have a chance to develop into bigger problems.

 

[vad]

quote:

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Originally posted by LarryL:

quote:

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Are those engine repairs only?
If not then the data is largely irrelevant and has no correlation to the length of oil change intervals.

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The subject is oci's and engine oil, the two main variables, no brakes, transmissions or electrical systems. Where did I get you get side tracked?

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quote:

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Originally posted by LarryL:
The biggest problem was cooling system failure.
These problems would stop a car and cause a lot of damage.
Next were, late in the 100k cycle were dirveability problems that related to smog and fuel control/system problems.
One problem found more often in the synthetic oil cars was top end wear and valve train noise, also only very late in the 100k cycle, though.
One of the reasons for changing the brand of synthetic oil was the valve train wear.

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No offence, I think you got yourself sidetracked big time.

Please post more info on the oil related engine problems.
So far I haven't seen any evidence/data proving that the longer changes with synthetic are more problematic as compared to the shorter intervals with dino.

 

[LarryL]

The biggest problem in down time and cost was the cooling system, agreed not oil. The oil related problems as stated were valve train noise and wear along with smog control, driveability and fuel control (again I understand gasoline is not oil). The cost of repairs and and downtime tracked were tracked on all engine repairs. The synthetic oil group experienced more repairs and down time if they needed repairs late in the cycle. Overall the synthetic oil cars were cheaper to maintain, including the ones that needed repair. My comment was that synthetic oil did a good job over all, but those engines that needed repairs needed more work. If I can not get this statement across I'll stop. There is no smoking gun, just a comment. It appears that the choice between short/conventional vs long/synthetic has no clear winner in cars well maintained and driven in moderate climate. I'll leave with that comment.

 

[JohnnyG]

We're not buying any of it! Keep working on the software. I see absolutely no correlation between fuel deliver issues and engine oil "group". Yes, you are just stating a fact, and maybe someone out here can see a correlation between the two, just not me. As to cooling system service, that should be a completely seperate issue as well, and service should always be done per the manufaturers recomendations, regardless of OCI frequency. Sorry. It's like saying cars that run extended OCI's run out of wiper fluid more often than cars on a strict 3000 mile OCI interval....perfectly true, and probably a result of fewer visits to the "quick change" place, but not statistically related in any way.