What do you feel is a reasonable OCI for synthetic

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Patman

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When this site first started it seemed most members would try to push their intervals as long as possible on synthetic, but I feel like that has changed in recent years and even my own way of thinking has changed as well, for various reasons. So I decided to start this topic to see what people on here now feel is a reasonable OCI using an OTC synthetic (not one of the extended performance ones either but something like regular M1, Castrol Edge or Pennzoil Platinum) When I say reasonable, I mean what OCI do you feel gives you good value for your money but also doesn't push the limits too far? For me I used to try and go a lot longer (10-15k in some cases) but I've now scaled that back a bit and feel a bit more comfortable keeping the OCI closer to 6k (which is a nice even 10,000 km for me) Is there anyone on here that still feels like they need to do 3000 mile intervals even with synthetic?
 
Both my BMW and Honda I change at 6000 km. Its about $40 to do an oil change ($29 on Honda, $50 on BMW) practically free.

I should also add, my cars get driven, hard, and get a LOT of short trips. I work only 5 km from home. Civic is a winter car that gets used on track in the summer, BMW is summer only but sees some track use and is significantly more HP than stock, currently 400 hp/420 lb.ft.
 
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Only the highest performance engines need synthetic changed every 3K. Outside of that, it really depends - my Cruze with the 1.4 gas turbo (port injected) gained a bad reputation in its first few years partly because the 10K OLM calibration was too much, especially for syn blend Dexos1 oil. They scaled it back to 7,500 before my car was made, but I've run 5K intervals because the car always sees some amount of mixed driving and I can waste 2,500 mi. worth of OCI for a long time before it outweighs the cost of a turbo. I run Schaeffer's syn blend @ 4-5K in my '85 GMC and Schaeffer's full syn @ 5K in my diesel Mercedes. If I had a newer, run-of-the-mill NA engine that saw a lot of highway miles I'd run 6-8K, maybe 10K depending on what it is, but there's a difference between what OCI will keep an engine in one piece for 200K and what will keep it spotless inside for at least that long. It depends.
 
Depends on driving conditions.

For a short tripper vehicle, then 5000 miles is still my max.

For a regularly driven vehicle with a mix of short and long trips, 7500-10,000 miles.

If only highway miles, up to 15,000 miles.

These numbers are for engines that do not have direct injection or boosted.

If I had a DI turbo engine, I would cut the mileage almost in half (so yes, 3,000 mile interval with synthetic on a short tripper vehicle).
 
Originally Posted By: Alex_V
but there's a difference between what OCI will keep an engine in one piece for 200K and what will keep it spotless inside for at least that long.


I think that's why my thoughts have changed recently, as I do feel that even if the oil can still do a decent job beyond 6k, I also feel that if I want to keep things spotless inside then I need to keep the intervals lower than I previously did. I do believe in getting more value for my oil filter dollar though and am going to be leaving my filters on for two intervals (except on the Corvette because of the powertrain warranty)
 
I use the GM OLM for my 2008 Chev 6.0, but that’s usually 6000 to 6500 miles. For me it works out to 2 changes per year: one after the winter and one after the summer. I buy SN Dexos approved synthetic oils on sale and don’t worry about the latest and greatest feature. 150,000 miles on my engine and runs great with no oil consumption. Knock wood.
 
Originally Posted By: blupupher
If only highway miles, up to 15,000 miles.

These numbers are for engines that do not have direct injection or boosted.

Because of the DI on my Corvette (and the 2% fuel I saw in my first UOA) I'm still not sure where my comfort zone lies just yet there. I don't plan on following the OLM just yet, my next oil change will be with only 3000 miles or so on the current oil.

For highway trips, I do feel confident that they put very little stress on the oil. So for example if we did a 3k trip on the BMW, I'd have no problem extending that particular OCI from 6k to 9k.
 
Completely depends on:

- Vehicle
- Usage
- Driving conditions
- Condition of engine
- Type of oil

Tons of cold starts and short trips in the dead of winter, engine prone to fuel dilution, tiny sump, low-SAPS oil: 3k seems reasonable

All gentle highway driving, moderate temps, low humidity, tight clean-running engine, huge sump, oil designed for long OCIs: 15k+

Track use: 1 session
 
I dont think I feel its necessary to do 3k intervals but I usually change my oil between 5000-9000kms. (3-6k miles) For me it depends on timing, I like to change oil in Spring once the temps are regularly over 7 or 8 degrees celsius so it depends how much Ive driven since last OC in November. So far Im only at 3300km, just over 2k miles, so I believe it is likely that I will change it in about a month at Im guessing 3k miles. Also, I bring my kid to daycare and get him twice daily 4 days a week and all are short trips about 2 miles return. I do get the oil hot at least once a week but figure I am severe service. Im not concerned about getting the most out of syn oil. Syn oil isnt that expensive once you consider 2$ specials or mail in rebates. Im quite content doing 3k changes but its not to say its necessary, pretty confident that 10-12k kms in a well maintained engine is a safe bet. Follow mfr recommended interval seems good to me.
 
Since the start of this website, OLMs have gotten better, manufacturers have generally extended OCIs a bit, and engine power densities have changed substantially...

I found long ago, with old engines and past-tech synthetic oils, that the non-severe duty OCI could be used in severe service when a good syn is employed.

That has not changed, IMO. The thing that has changed is more and better OLM algorithms have directly informed if severe service is incurred. I think that generally their findings reflect the finding I had years ago.

So following an OLM is an appropriate approach, with the correct spec oil.

Following the non-severe service interval with employment of a quality syn oil works.

If one is truly running a severe service, UOA is prudent to determine if it is affecting modern formulated oils.
 
Way too many variables involved to make a blanket statement. I believe this is why more and more manufacturers are transitioning to OLM systems. That being said, they're not all as accurate as GM's and doing a few UOAs to gauge their accuracy is important. Using my Mazda as an example, it doesn't seem to factor in cold weather/idle nearly as much as it should which is why I see fuel dilution during winter OCIs.
 
I do realize that there are a lot of variables in play, and this was more of a discussion to find out what everyone is comfortable with doing for their own situations, not that I was looking for advice for myself. It would have been cool if we had done a poll at the beginning of this site in 2002 and then did another one today to see if the overall average OCI for members has changed.
 
It's heavily dependent on the vehicle, driving conditions and the environment; in my case it's usually one year because of the lack of miles I put on my cars. If time isn't a factor I go by the OLM in the BMWs and the Mini. That works out to:

M235i- @10,000 miles
328i- @15,000 miles
318ti- @9,000 miles
Clubman- @15,000

Based on multiple UOAs my Mazdaspeed 3 could go up to a 10,000 mile OCI, but I went with the factory recommended maximum of 7,500 miles. It was running great at 158,000 miles when I flipped it for the 2er.
 
Originally Posted By: Patman
I do realize that there are a lot of variables in play, and this was more of a discussion to find out what everyone is comfortable with doing for their own situations, not that I was looking for advice for myself. It would have been cool if we had done a poll at the beginning of this site in 2002 and then did another one today to see if the overall average OCI for members has changed.

Ah, got it. Guess I misunderstood. Definitely an interesting question.

With my previous cars, I'd probably have used oil analysis to push the limits. 10k-15k+ if I could.

With my RX-8, I'm sticking with conventional for warranty-related reasons. But if I did switch to synthetic, I still probably wouldn't go beyond 3k.
 
Originally Posted By: Patman
I do realize that there are a lot of variables in play, and this was more of a discussion to find out what everyone is comfortable with doing for their own situations, not that I was looking for advice for myself. It would have been cool if we had done a poll at the beginning of this site in 2002 and then did another one today to see if the overall average OCI for members has changed.


I have definitely changed my practices regarding OCI. I followed the 3k oil change recommendations for many years, eventually creeping up to 4-5K miles on conventional oil. With my current vehicle (2014 Jeep Patriot) I follow the OLM, but never over 7K miles with Pennzoil Platinum. I have no experience with turbo engines and GDI, which might influence future practices. At my workplace, I have increased my intervals for filters, coolant, etc. based on my experience. Often those manuals recommend annual changes regardless of hours and conditions.
 
For me a reasonable OCI backed up with UOA would be right around the 6K mile mark. I keep it simple 5K miles or a year in my Rubicon, 6K miles now in my Liberty, my van is pushing 2 years now. There is no way an OTC synthetic would last 10K miles in any of my three vehicles based on the UOA's I've had done.

Bottom line, it varies by how the vehicle is used and driving conditions. Following blanket statements on blind faith can get you in trouble.
 
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