This seems like a dumb question but I have never run a synthetic oil before so I am not sure how often I should change my oil in my 2005. I usually change it every 3,000 miles but I think synthetic will last longer. Any suggestions?

 

There are a number of threads on the subject but IMO, you keep the same interval -

 

There have been many people on the board that have many different responses ranging from 500-3000 miles do a search and im sure you will be able to find what you are looking for.

 

[quote=I8URVTEC,July 5, 2005, 10:13 AM]
This seems like a dumb question but I have never run a synthetic oil before so I am not sure how often I should change my oil in my 2005. I usually change it every 3,000 miles but I think synthetic will last longer. Any suggestions?

I agree with Ed and Sal. For those of us who use full synthetic motor oil we still adhere to the 3000 miles OR 3 months interval. I take note when I hit 3000 miles and make sure I change by 5000 miles. Since contaminants build up over time and sit in your oil the mileage AND time interval minimize contaminants causing any type of acid/crrosive damage to your bearings and top end over time.

 

Keeping the same interval is incorrect. You can run synthetic oils longer than Dino oils. Whomever told you guys that is incorrect. You can run synthetic oils for 5K plus, but first I would recommend this....
www.blackstone-labs.com

 

I'd say that since Ford says 5,000 miles in the manual, that'll probably work just fine. I mean, they did build the car.

 

Mobile 1 new oil say's 15,000 under normal conditions. Seems like alot but they make the oil and want to sell it, so why would they strecth the milage if it wasn't true.

 

[quote=max2000jp,July 6, 2005, 12:16 PM]
Keeping the same interval is incorrect. You can run synthetic oils longer than Dino oils. Whomever told you guys that is incorrect.

If you monitor your oil with samples from Blackstone you might be correct...but once you operate your vehicle after a new oil change you have introduced contaminants. The 'time' interval is there because even though you're not running your vehicle the contaminants can still create havoc on your soft metal bearings or your top end(valve train). The interval is there because damage can still occur even if your car sits idle. If you use Amsoil I would definitely change at the time interval. Mobil 1... Royal Purple...even Red Line can be extended to 5000 miles. It all depends on the affinity of the oil you use to create acidic corrosive conditions in your engine.

 

[quote=MJC302,July 7, 2005, 9:55 AM]
Might want to retract your statement on Amsoil there. Do a google search, you will find a lot of good information. If you change your oil at 3K, you are wasting your money.

 

[quote=max2000jp,July 7, 2005, 11:07 AM]
Might want to retract your statement on Amsoil there. Do a google search, you will find a lot of good information. If you change your oil at 3K, you are wasting your money.


I've read the 'long winded' discussion on the Boss302 Mustang site by a person who tested oils for many years. Amsoil is a good oil but is loaded with more additives than most other synthetic oils. More additives...less oil. All of the info I have seen about Amsoil is usually by Amsoil distributors..etc. I go with the people who know. The discussion of this thread is 'interval' vs mileage. Amsoil loads their oil with additives to give the 'extended' mileage. Not a selling point. If you keep to the 'interval' you can't go wrong..no matter what oil you use. That is the main point. Frequency=longevity. When you consider the cost of the Mustang vs $50-100/yr for oil changes...it seems like a moot point?! Wouldn't you say?

 

[quote=MJC302,July 7, 2005, 10:20 AM]
Let me try and find an excel file from the maxima forum I used to belong to. One of the mods over there compiled all the oil analysis data and used it to come up with some independent conclusions. Also, there was a good article written by LS1 owners that showed how oil holds up under long intervals/mileage.

 

The more info the better. As a Mechanical Engineer I am always open to true 'real life' empirical data.

 

Here is thread, download the spreadsheet:
http://forums.maxima.org/showthread.php?t=100060

 

This is the LS1 test I was talking about:

http://neptune.spacebears.com/cars/s.../oil-life.html

Both offer pretty decent data where you can come up with your own conclusions. Best bet is to get an oil analysis, such as Blackstone, which will tell you how long you can run a specific oil.

 

[quote=max2000jp,July 7, 2005, 11:40 AM]
This is the LS1 test I was talking about:

Both offer pretty decent data where you can come up with your own conclusions. Best bet is to get an oil analysis, such as Blackstone, which will tell you how long you can run a specific oil.

Jason...I enjoyed the neptune article but could not download the spreadsheet off the Maxima site(up to 6 different viruses in the file and couldn't scrub them)

The test had the LS1 engine run on Mobil1 during the 9939-27960 odometer reading of the car. Amsoil was put in for the 30976-44970 odometer mileage.

Amsoil quotes from the article:

2000 mi...Amsoil lost 50% of it's TBN, Mobil1 only 30%
7000 mi...TBN lower than Mobil1 at 12,000 miles
8000 mi...Amsoil oficially a 5W-40, "we would have quit here..."
11000 mi.."we are suspicious of the lower metals in the Amsoil sample...suspect it has to do with the older mileage of the car"
12000 mi...17% drop in fuel economy.."Bad news for an engine that prefers a thinner oil"
14000 mi..."Amsoil is now officially a 15W-40"...from a 5W-30.

Some Mobil1 quotes:

3000 mi...TBN higher than new dino oils
14000 mi..thickening, but not out of grade

Retest of Mobil1 after the Amsoil testing showed copper present in the oil to be 1/3 of the Amsoil sample after 1000 mi.

The article goes on to say they recommend more frequent oil changes during the first year, then extend when older.

Based on the way Amsoil thickens over time I now would not even think of putting the stuff in my Mustang..or even my lawn mower.

My apologies to all who use Amsoil. You may now beat-up on me. :worship: :worship: :worship: