how long to go on synthetic?

[Hitchhikingmike]

I was wondering, I have never heard of any commonly understood mileage range one should go on their synthetic oil when used in their engines.

I know with regular oil the intervals are 3,000-4,000 miles between changes.

What is the "recommended" interval one should go with synthetic oil?

With synthetic, what mileage would be pushing it to get the longest life out of the oil, and what mileage range would be considered to be an "early" change to help protect the engine even more (such as the 3,000 mile mark with mineral oil)?


Thanks.

 

[CDW6212R]

Look at Amsoil, they make a filter for their special oil, they suggest up to a 25,000 mile interval. I have gone over 12k with my work truck, for severe duty only run it 12,500 miles or a year. That method will cost you about $55 or so per year for the oil/filter, cheaper than any normal oil interval system. Regards,

 

[Hitchhikingmike]

I have always wondered about the these super long intervals though. Most of all my miles are short, in town driving.

I have often wondered a lot about condensation in the engine. If you went this long without an oil change couldn't this introduce a new potential problem with too much water/condensation and other elements building up into the oil with all city miles?

 

[CDW6212R]

The most important item to keep the oil clean is the air filter, do not skimp at all on that. Buy the very best air filter possible, one which cleans best, not outflows(K&N) others. Amsoil makes excellent air filters, which I have. Al Aldive here has the same filter and oils as I, he started long ago. He has run way past 25,000 miles with Amsoil, and tested the oil several times along the way.

I had no apparent oil use at 9,500 miles, the dipstick showed full and the oil was still transparent. That kind of quality isn't found in cheap oils and filters. 99% of oil contaminants get into it through the air filter.

 

[Hitchhikingmike]

Thanks for the info.

I have also wondered what is best, frequent changes with mineral oil, or just going with synthetic for long intervals. I guess the best solution to either is just to use a good air filter?

What are outflow filters? Are you referring to cone shape filters that replace the stock air boxes? Which do you think provides more protection?

 

[Hitchhikingmike]

Also, I think I've made up my mind to use synthetics for now on. I think the battle now is Mobile1 vs Amsoil. How do I possibly decide?

This page does a study between the two, but I think one still does not outshine the other. Although their studies showed that after age Amsoil thickened up out of spec while Mobile 1 did not.
http://neptune.spacebears.com/cars/stories/oil-life.html

What is this with Amsoin making up excuses in the past for not having their oil certified? Any one know?

 

[Russ in CT]

Not 'Outflow' filters, rather, filters that outflow other types of filters (filters that offer less restriction, such as K&N).

A K&N filter is made of gauze (like medical bandages), that is soaked with oil. It flows better a lot better than most paper filters, thus can often improve hp and even mileage. There are other brands of performance filters that use other technologies, but the idea is the same, better airflow.

It stands to reason however that more air means more dirt, too. Its easy to make a filter that allows more air, at the expense of dirt. Its easy to make a filter that blocks more dirt, at the expense of air flow. Its certainly a challange to make an air filter that flows more air while still blocking dirt as well as stock.

 

[calisoundmix]

i'm approaching 10,000 miles on my amsoil oil and as of the last oil analysis (@7,000 mi.) it still was holding up great and keep in mind this is on a stock engine, the amsoil filters perform superb as well.

 

[CDW6212R]

Thanks Russ, well said. Most used oil loses viscosity and most of the additive qualities. Amsoil changes less in those factors than any other oils.

Synthetic oils can be grouped into about two levels, and Mobil 1 is not in the highest level.

 

[aldive]

I have always wondered about the these super long intervals though. Most of all my miles are short, in town driving.

I have often wondered a lot about condensation in the engine. If you went this long without an oil change couldn't this introduce a new potential problem with too much water/condensation and other elements building up into the oil with all city miles?

If in doubt do a UOA.

 

[aldive]

Take a look at http://www.explorerforum.com/forums/showthread.php?t=134084&highlight=uoa

 

[Hitchhikingmike]

Thanks for the info, I understand synthetics a lot better now. I had no idea that oil samples could be tested!

However I am now baffled about air filters.

I was considering purchasing a K&N cold air intake to increase MPG, but not at the expense of allowing more particles to pass through the air filter.

Who do you think makes the best air filter in terms of filtration (disregarding the volume air flow)? Amsoil?

Are there any outflow filters that do not compromise at all the quality of the filtration? Or is it just a basic understanding that the more flow you have the more you lose filtration?

Thanks.

 

[aldive]

Who do you think makes the best air filter in terms of filtration (disregarding the volume air flow)? Amsoil?.

Amsoil, without a doubt in my opinion.

 

[rizzjc]

I've been using the Amsoil EaA air filter for a few years now, and have no complaints. The claim is that although the K&N allows more air flow, it also degrades a lot faster. Amsoil claims to have more consistent flow, for the life of the filter. I just blow or vacuum it once a year (or when I think about it), and it's guaranteed for 4 years (though will probably last much longer).

As for oil, 158k miles on my '97, running Amsoil since about 10k miles, and change it every 10k-15k, sometimes based on an oil analysis, as I've done them a few times, just to backup my interval.

 

[CDW6212R]

That's nice, I'd like to see inside that engine whenever it gets pulled.

 

[rizzjc]

Well, I've thought about it, but an engine rebuild is a little beyond my capabilities right now. I have been losing some oil, and recently switched from 0W30 to 5W30. It seems to be losing less now. I get no smoke though, but it's not leaking out, so I have to be burning it. I did take a hot engine and dump it in cold water ...
<-------------------
so, it can't possibly have liked that too much. I kinda ruined my "test vehicle". But, at 158k miles it's still going strong, albeit with a little power loss from its glory days. That's pretty good, and I saved a lot of time and money on oil and oil changes over the years. But if the UOA doesn't show anything bad, then what would you be concerned about seeing when the engine was pulled?

 

[CDW6212R]

Not many engines get top synthetic oil their whole life, I'd like to see how little wear there could be. Semi trucks get 100's of thousands of miles before rebuilds, mainly due to their special bypass oil filter systems. Amsoil sells those for as little as about $150, I plan to use those starting with my 347.

You likely have some wear in the valve stem seals, that would eat a small amount of oil without making smoke. As they got worse you may see a little smoke at start up. If it was a lot to worry about, you might try an additive that is for expanding seals, that could help slightly. I've been very pleased with my SOHC truck, other than the fuel mileage. I was hoping to do better than my OHV 93 truck.