How many miles do you go before you change your synthetic oil. Most say 5000 miles, some say you can easily go 10,000 and some say the Mobil One factory has said (a long time ago) that you can go 25,000 miles. Thoughts?

 

I suppose you could go 10,000 miles but I would still change oil filter every 2,500 miles as oil is still going to get dirty! JMO

 

try the oil and lube forum

 

Despite claims, opinions, and campfire stories, change your oil by the mfg recommendations. *Esp. if still under warranty.
Running supposed high mileage oils to their max mileage just keeps more dirt circulating in your engine.

OR- If you insist on running oil as long as possible, set yourself up a method.
Beginning with a fresh oil/filter change, check your oil at least every other tank of gas. Keep simple notes for a while on how the oil looks and especially any level changes, and mileage of course.
Once the oil starts looking/smelling dirty and you start noticing a drop in oil level, that should be a sign that it's time to start scheduling an oil change.
Once you've done this a few times, you'll know how far in miles you can go between changes.

 

well smell or color play no part in it. only a uoa can tell you how far you can go. try BITOG

 

If you want to get technical/scientific about it.
Anyone that's been around vehicles for a period of time can tell when the oil is getting dirty/beyond clean.

Smell, color, and the oil as it looks and feels between your fingers is still a good in the driveway appraisal of 'is it time to change'. You don't have to pull out the chemistry set every time.
Good grief, it's just an oil change. You want to have it analyzed annually, great, but not between every change.

 

no but setting a oci trend can determine optimum oci's. so a few uoa's can help determine your oci.

 

Moved to proper forum.

 

Depending on brand of synthetic oil you buy and the brand of car you drive you sould change oil every 10,000 to 20,000 miles. Have the oil tested a few times then you well know.

 

BMW and Mercedes allow up to 15,000 miles under warranty, but with limitations. The on-board computer decides on its own what is "severe service" and adjusts the service indicator system accordingly. Only ACEA A3 synthetics are approved, not just any API SL or SM ones.

Dont violate your warranty. If the book says 5000 and Mobil says 15,000 and Amsoil says 25,000, I think I will use much less expensive dino or blends for the first three years. After that, once-a-year changes with synthetic may be a viable option. I would still do at least one UOA to make sure.

Jim

 

I use syn in everything, my religion.

I change at the "Normal" duty interval in the manual. On Fords usually 5,000, on GM 7,500. If I was running dino I would go with "Severe" duty cycles.

I once long ago tried 15,000 mile changes but I didn't like the look and smell of the oil so I reverted to the "normal" schedule. There is also the irritation of changing the filter half way thru. I figure if you are going thru the trouble and mess of changing the filter, you might as well change the oil too.

I tow an 8,000# trailer with my 94 F2504x4 460 and Valvoline syn. My work car(currently Lincoln LS) gets Mobil 1 for mostly freeway driving with some stop and go. My wife's Mercury Villager van gets Havoline Syn but I may switch due to difficulty finding it lately. I may go with a cheap syn or even try Wally world for the van.

I use Mobil 1 out of habit since that is the first syn I "discovered" back in 1980. I use Valvoline because I always liked Valvoline in the 70s but they didn't have a syn until I bought my truck. I use Havoline because it is about a buck cheaper and I don't feel guilty using it in my wife's "Lesser" vehicle.

Jim Henderson

 

There is no one general answer for the question you ask. Synthetics cover a variety of oils, formulations and basestocks. I certainly would not run any Walmart synthetic oil over 5,000 mostly because it is not designed for the extended oil change interval. Mobil One is not specifically designed for extended changes but performs almost as well as their Mobil 15000 which is designed to go the distance. Amsoil is another that is designed for the long haul but its additive package puts it outside of the API limits on the add pack. Redline, while good oil, is not known for having good results for extended changes. Royal Purple would fit into the same catagory. Good oils but not designed for that intent. If you have a gas engine, unless you pull a trailer daily, prolonged idling, or have temperature extremes, you don't NEED a synthetic. No synthetic basestock, Gp III, GP IV, or Gp V, will add one mile to the life of your engine for the average user. There is no more lubricity in synthetic basestocks over a dino or a blend. Most accolades to synthetics are advertizing hype. The blends will show the lowest wear metals, generally. If you have a diesel and are wanting to use extended oil changes as a maintenance downtime advantage, consider also a by-pass filter. Amsoil and Mobils Delvac One are on the top of the game in this arena.

If you want to do the extended oil change intervals, you need to trend your engine under normal conditions. This is accomplished by having the oil analized at prescribed mileage intervals. Example: If you have a PSD and are using Delvac 1, pull a sample at 10,000 miles, 15,000 miles, etc and let the results of the trend be your guide. Your reports will show you when the life of the oil is just about over. So lets say we have a TBN of 1.2 at 20,000 miles and everything else is normal. The life of the oil is just about spent. We need to change the oil. Next oil change have the oil sampled at 15,000 and compare it to the previous 15,000 mile analysis. If it is similiar, you know that it is due for a change at 20,000 miles. Extended oil changes can be a valuable tool for maintenance down time. But, if you don't want to perform the complete package via analysis, stay away from it. Your engine is not a cheap item to replace.

 

I personaly feel that unless your turning some serious mileage why push things to the ragged edge. Take the following two instances: my pickup (03 CC SB 4x4 V10) I change the oil at 2000 miles with motor craft 5w20 and the matching motorcraft filter. My dad gives me he!! for dumping oil thats in better shape then some of the old stuff he used to dump in back in the 60s-70s. I look at it this way, I drive my truck only 6-8k miles per year so say I average 4 changes per year thats only one every three months so I spend 30mins and $18 every three months which equate to 2 hours of my time per year at a total yearly cost of $72 (retail) say I own this truck for 7 years, thats only 14 hours and $504 to properly maintain my truck for 7 years, lets just say that for the minimal cost and time it gives me a piece of mind.

The second instance is the wifes car in which I change every 3,500 miles with castrol sythetic blend and either a Napa, Wix, or any decent filter thats I can find on sale. Now it cost me $14 to change oil on the car we drive an average of 20,000 miles a year on it so it gets changedabout every 2 months so agian 1/2 hour and $14 to change the oil six time totals 3 hours and $84 for the entire year.

If I had to replace the engine in my truck it would cost somewhere in the neighbor hood of $3,500-4,500, the car would run considerably less at around $2,500. I look at it as I spent 35k on to own a new truck, $600 per year to ins. it, another 100 to register it, when its paid for it'll still have a good value, another $70 a year isn't gonna break me and if it was I shouldn't own the truck anyway!!! seems kinda minimal to spend $70 on oil changes when I figure It costs me $6100/year just to own it!!! the car has been bought and paid for since the day I picked it up but its the same deal, whats $80 a year!!

Consider this, my daily driver is an 89' buick lesabar and has 275,000 miles on the ticker and still runs great, the trany is extremly weak but the engine doesn't miss a beat and has never been opened up for anything!! The only thing this car has ever gotten is regular old dino oil with a filter change every 3,500 miles.

Lastly if a person cann't afford to spend the time or money to change the oil I cann't imagine the rest of the filters and fluids look like!!! I not only change the oil but I take car of the rest of my vehicles with regular air filter (2 per year) & fuel filter (1 per year) replacements, anitfreeze drained and replaced once a year, powersteering fuild flushed every 3-4 years, trans fluid changed every 30-40k and of course the transfercase and front and rear ends on the pickup at regular intervals. I figure If I cann't afford $600 a year to maintain 3 vehicles with a total value of around 45k (the buicks not worth more than a thousand bucks) I shoulnd't own them!!! Just my take on things, to all there own.

 

I wholeheartly agree with that!!!

 

I used to work at a dealership, and a ditzy girl in a cavalier came in for her first oil change at 50,000 miles! The car was still running, and if you didn't pull the dipstick, you would never know that the car was running with 50K mile oil in it. I believe that you guys over analyze oil. Your car will never know the difference between a 7,500 mile oil change, and a 10,000 mile oil change. It will also prob never know the difference between syn and dino. Just my opinion.