Motor oil

[bill crommett]

This afternoon I had the engine oil changed in my BFT. The man asked me if I wanted to switch to synthetic so I could get 8 to 10 thousand miles on a change. I always believed that dirty engine oil did not belong next to the wearing parts of any engine, so I told him "no thanks" Then I got to thinking : Just what is "synthetic" about the synthetic oil ? I don't have any petroleum engineers for neighbors, so I have to bug my panel of experts here on the "knowledge of all things on wheels" site.
All replies appreciated, but please use one or two syllable words when possible.

[Mel Wilbur]

Bill, this is a subject that is very personal so all I can tell you is I use Amsoil 5w30, change the filter every 5,000 miles and the oil at 15,000. I am sure many will not agree with this but it works for me.

[bill crommett]

Mel: Thanks for your opinion, but I would still like to hear about what "synthetic " is.

[Steve W]

Bill

As Mel says, it is a personal decision with any number of variances. For our 24RB, I use Castrol 5/30 Synthetic with a K&N oil filter. The change for both is made every 6,000 miles. There are some who would say that the change is premature, but again it is a personal decision.

[Dallas Baillio]

Here is a Wikipedia link that explains synthetic oil. I imagine there are other better links. This one is from a quck Google search. Hope this helps a bit.

http://en.wikipedia.org/wiki/Synthetic_oil

[Steve]

Well I guess I'll throw in my 2 cents worth here. We use Redline synthetic oil, I change every 12-15 thousand miles and change the filter every 6000 miles. I picked up about 1/2 MPG after I switched to synthetics. I like the Mobil 1 oil filter.
Here is the URL for redline: http://www.redlineoil.com/products_motoroil.asp
I'm currently using 5w-40.

Steve

[Robert D. Grant]

From the research that I have done I believe that using synthetic oil is a waste of money. I have never used it and have put over 100k on a number of vehicles with no engine problems. Everyone pushes it because there is more profit in selling it. This is especially true these days when the shops are hurting financially and looking to make more profit by selling people things they don't really need. There is a study that was done on NYC taxi cabs and the engine teardowns after many (100k?) miles showed no difference in wear between engines with synthetic or "normal" oil. I believe that there are previous posts on this subject. Our Born Free is a diesel with 100k miles on it using Shell Rotella with filter and oil change every 5k. The engine (and trans) has been perfect (knock on wood). The maintenance book says you don't ever have to change the tranny fluid on an EOD trans, but folks I know personally that worked at a GM Transmission Plant said that the first thing they do when they buy a new car or truck is to have the trans fluid replaced due. I had ours changed at 20k miles. The only major money spent on the chassis was new brakes (discs and calipers) on all 4 corners about 4 years ago when the unit was 6 years old. Since then I have had the brake fluid changed every year as a precaution. Less than $100 for brake system flush vs $2500 for new brakes. Brake fluid as well as other fluids (like power steering fluid) absorbs water and needs to be changed perodically although there is no mention of this in the Ford maintenance manual.

[bill crommett]

Thanks for your support, Bob. I had heard about the Taxicab study, but I filed it and forgot it because there was no statistical comparison that put the constantly warm engine of a taxicab engine against the intermittent use of a private passenger engine that was allowed to get cold between starts.
Because I have always believed that dirty engine oil which carried carbon and ground up metal did not belong next to cast iron or aluminum, I guess that my next two research projects will have to be concerned with the holding capacity of synthetic lubricants, and the price comparison with the interval changes and the hassle factor of appointments and waiting times listening to commercially motivated "experts"
Bill .

[Robert D. Grant]

By the way, I keep seeing statements that lubricants, frequency of changing, etc are a matter of "personal preference". The engineer part of me (40 plus years as an automotive manufacturing engineer) has a problem with this kind of thinking. Decisions such as this should be based on facts and data, not opinions or tradition ("my daddy always did it this way"). Not that I think this will change anyone's mind that thinks this way. For some inexplicable reason, no one seems to read the owner's and maintenance manuals that the manufacturer's publish (and that includes engineers that I have worked with!!). I hate to see money (and precious oil) wasted by changing oil every 3k miles "like daddy used to do". Well daddy drove a 53 Packard and that might have been called for back then, but with today's technology (in both lubricants and powertrains) this is definitely not required. Most new vehicles have an indicator that lights up on the instrument cluster to tell you when you need to get the oil changed based on a computer algorithym but people still blindly get the oil changed every 3,000. My Saturn Vue (tow vehicle) light comes on every 6,000 to 8,000 mile depending on how it's driven. Long trips with fewer stops equal longer intervals between changes.

[Robert D. Grant]

Bill,

You did exactly the right thing when you said "No Thanks". When my sister (a widow whose husband always took care of these things and never talked with her about it) took her vehicle to Sears (I could write an article about that choice of shops) recently to get the oil changed and tires rotated, they recommended that she change to synthetic.

I recommended that she change shops, not the type of oil, and use the type of oil recommended in her owner's manual (which she has never looked at by the way).

Bob

[Roger H]

Hmmm slippery subject, this.

In layman's terms (and I barely understand those...) there are two reasons to switch to synthetic... first is oil longevity. The synthetic oils don't turn acidic and lose their lubrication properties nearly as quickly as dino oils. That being the case, their lubrication properties help engine longevity, especially during cold starts. They flow better and lubricate faster.

I can't quote studies I've read as it was some time ago, and I don't have links at my fingertips but, the studies I read a couple of years ago when I switched everything over to synthetic was that they'd torn down 200k engines that had no appreciable wear from stock clearances after using exclusively synthetics.

The last thing about synthetics is that because they don't break down, you can run them until they do... and having the oil tested at infrequent intervals (like 6k miles or so) will tell you when it is time to change oil. Using 7 quarts at $5.50/qt, a run of 20k miles between changes is pretty cost-effective. Sample the oil in the filter when you have it tested, and then replace the filter every 6k miles or so. That should solve the majority of the suspended particles problem.

Roger

[Mike Jean Bandfield]

In '78 I bought a new Accord. After a 10K mile break in period I switched to Mobil 1 for several reasons.

• 1. I was doing so much traveling in the upper mid-west that I didn't have the time to get an oil change weekly.
  2. I'd read a Popular Mechanics article that suggested you could go 100K miles between changes using Mobil 1. They had a lot of data to back up the claim.
  3. The filter on the Honda engine was mounted above the oil level and could be replaced w/o tools in seconds. I could easily make the change and top off while filling with gas.

I decided that I could simply carry a box of filters and a quart of oil with me and I'd change the filters every 2000 miles - to be on the safe side. I also noted that it took about a cup of oil to replace what was discarded with the old filter. That also seemed to work with my new system because it systematically replaced the older oil with new.

After about a year and ~40K on the car (30K on one oil change and 15 filters) I noticed that I was adding more than a cup every 2K and went back to the traditional dino oil and 3K changes.

Long story short: When I traded the car in @ 52K miles it was using a pint between changes and there was telltale blue smoke in the exhaust.

There's a school of thought that says the high reving Honda caused the thin synthetic to foam which caused a loss of oil pressure -blah blah blah. However, I ran into a farmer one evening in Minn and over beers we traded synthetic experiences. His mirrored mine line for line except - his pick-up was a 327 Chevy.

Bottom line: I now change my dino oil every 3K miles (maybe 3500 - 4000 miles if they're easy highway miles) and my vehicles consistently go ~200K+ miles and then I trade them.

[bill crommett]

Thank, Mike. I will coment further after I hear from my old buddy , a retired Mobil salesman.
Bill

[binsjohn]

I have been using synthetic oil in my vehicles since 1979. Mostly Amsoil, but occasionally Mobil 1. In the earlier years I waited until the new vehicle (car, truck, motorcycle or boat) had about 5000 miles on it before switching from petroleum-based oil. This was necessary because synthetics are so much slipperier that they wouldn't allow the piston rings to seat properly and oil consumption would be higher as a result.

In recent years, however, internal combustion technology has advanced to the point where they don't need to be broken in. In fact, the reason why break-in is still recommended by automotive manufacturers is because transmissions are subject to different forces and still require time for them to wear in before applying maximum loads.

Here are a couple of "recent" examples:
• All Corvettes since 1994 have been shipped new from the factory with Mobil 1.
• My 2008 Acura MDX was delivered with 100% synthetic oil in the engine.
• The same is true of my 2009 VW Jetta Sportwagen TDI (diesel).
• The same was true (gone now) of my MB SLK55AMG.
• I installed Amsoil by-pass and full-flow oil filters and synthetic oil in the 2002 Chevy 2500HD with Duramax diesel that I used to tow our fifth wheel all over the country for over 80,000 miles. I made the change at the first scheduled oil change. After that I sent an oil sample to an independent lab for testing every 10,000 miles. The results of the first test test showed everything to be normal except for one trace metal. The lab report said that trace metal was to be expected during the early life of the engine. At the next test, 10,000 miles later, all parameters were good and the oil itself showed no signs of breaking down. I continued this ritual, changing the filters on Amsoil's schedule, until the day I sold the truck and fifth wheel. Bottom line: only one oil change in 80,000 miles. This is not unusual. Many commercial truckers use the same method and save lots of money on oil changes and repairs while getting measurable increases in fuel mileage.

I have heard many opinions on this subject from well-meaning people, including professional auto mechanics. Most of those folks had no real factual basis for their opinions. It takes well thought out laboratory testing and lots of real world data collected by large fleet owners to come to any reliable conclusions.

If you really want to know what is the best thing to do for your vehicle, I suggest you google the subject and look for information other than opinions. Personally, I have found lots of good info through Motorcycle Consumer News, Amsoil, Popular Mechanics and the owners manuals of my vehicles.

[BFrees]

I asked my mechanic about changing over to synthetic oil. I had about 40k miles at the time. He strongly recommended that I not change. He said that if I had switched over at lower miles and continued with synthetic it would have been OK, but in his experience to do so at 40k was asking for leaking problems.