Engine Oil

Which Engine Oil is Best for My Mustang?

Mustang Question & Answer With Heather - Engine Oil

Fluid Factoids Part I: The Mystery of Motor Oil – Synthetic vs Conventional

Question: How do I know what type of engine oil is right for my car?


Image from Lawnsite.com

If you Google this topic you’ll get thousands of different answers from thousands of different sources.  The debate over engine oil has been raging for decades and spans far beyond the age-old “synthetic vs. conventional” dispute.  Oil is the lifeblood of your engine and without it–well… you know what can happen.  So if you’ve ever found yourself standing in front of the “wall ’o’ oil” at the local parts place with a blank stare and a puddle of drool slowly accumulating under you, then hopefully this article will help make your next oil purchase a little less er… drooly.

Oil “Au Natural”

Old-head racers have preached the gospel of conventional oil since synthetic stumbled onto the scene back in the 70’s, but technological advances have left conventional oil in the dust.  The term “synthetic” is really a misnomer – synthetic oils are made from the same base ingredients as conventional oils.  Chemical reactions are then used to re-form the molecules to obtain desired characteristics. In a sense, synthetics are really just genetically modified conventional oils.  Synthetic oils (such as Royal Purple) can withstand extreme engine temperatures and have a much wider range of viscosities (down to 0W-30!) making them a no-brainer when compared to conventional oils.  All that comes at a price, however – $4 – $5 more per quart – so to get the benefits of synthetic at a price that’s easier on the pocket, a synthetic blend would be ideal.

Variations on Viscosity

The Golden Rule of oil viscosity set down by the automotive gods is this: ‘Though shalt use whatever thine manufacturer specifies.’  This holds true for most applications – check your owner’s manual for the proper weight for your vehicle.  Viscosity is the measure of a liquid’s resistance to movement – the lower the number, the less viscous (or thinner) the oil.  Dual-weight oils have become the norm for modern cars (ex. 5W-30) – the first number being the viscosity at 0˚F (aka “winter weight”), the second is the viscosity at 212˚F.  Oil is engineered to be thinner at colder temperatures to provide the least resistance at startup, since that is when most engine wear occurs.

The 3,000 Mile, $64k Question: Mustang Oil Filters

Mustang oil filter and oil change intervals can vary from one car to the next.  2010 Mustangs set the oil change interval at 7,500 miles/6 months (under normal operating conditions); this is another case where your owner’s manual comes in handy.  Your Scheduled Maintenance Guide will tell you whether you should follow the normal maintenance schedule or the special operating conditions schedule.  It’s better to err on the side of caution – you won’t hurt anything by changing your oil every 3 months/3,000 miles so if you’re not sure which schedule to follow you can always default to the tried-and-true.

In the world of aftermarket modification it’s easy to stray from the manufacturer’s recommendations, but this is one area where you want to rely on your owner’s manual for support.  Replacing your oil with the proper weight at the specified intervals is one of the easiest ways to make sure your Pony keeps kickin’ for years to come.

Written by Andrew

"You're telling me it's got four wheels, two seats and goes faster than the speed limit? Good, I'm driving."


  1. What seems to work for me… My 96GT, it seems to only “like” Castrol… just the regurlar, nothing facy, no syntechic, etc. My 07 V6 couple seems to work better and shift smoother with Castrol full syntechic… anything else … let just say it seems to be pissed off.


  2. I use 5-20 mobil 1 in my 07 stang GT. I change it at 5000 miles and it is allways clean.You must use a premium filter also. I only use K-N oil filters.


  3. I use Castrol High Mileage, works just fine. I still drive it like I stole it, poor stang you had to come with such power just for me to push it to the redline. 🙂


  4. use royal purple synthetic in everything. ever 6-9k and its clean. minus the first change over from conventional to RP. then you need a 2500-3k change and ur good.


  5. call me old fashoned, but regular ol penzoil, every 2000 miles with a new filter.

    costs a bit more to do it more often, but as stated, nothing wrong with clean oil.

    oil must go atleast 1k before it breaks down to work properly. so 2K is a prime number.

    this is a good write up, but with 326,398 miles on my dodge motor, with regular ol penzoil, i dont think twice about dumping it in the stang 😀


  6. I use Ford Motorcraft synthetic blend. My dad has a ’02 F-150 with 132k miles on it and after 8 years he hasnt had one single problem. Thats what i run along with a K&N oil filter, runs beautifuly


  7. i just put 5w-20 in my 02gt like the oil cap says 2 do and it works =p kinda sucks tho since i gotta buy it in individual quarts since they dont sell it in 5qts.. not that ive found anyways.


  8. Only Royal Rurple for this Mustang…I live and die by that stuff. Ever since I made the change a long time ago (first oil change at 6k), the car runs clean and smooth.


  9. Mobil 1 5W-20 Syn. is my oil of choice, you must also use a Mobil Filter to reap the benefits of the top shelf oil. I work in the oil business and Mobil has been my choice for everything for years no matter the weight. Our 96 pony has over 200K and so far no engine issues and we also have an 09 GT that gets the same treatment. Face Pegasus was just a pony with wings!


  10. I have a 05 v6 (wish gt lol) and use castrol syntec with k&n oil filter also z-max evey 3,000 miles. Kinda expensive, but I feel more comfortable with that in my car when I gun it!


  11. I own a 2004 V6 (been looking for a V8 but yet to find just the right one). I’ve owned my stang since March 2006 and she is my daily driver, so when I finally made up my mind to stop taking the lazy route and paying $40 for someone else to change her oil I started doing it myself and swapped over to Royal Purple 5w-20, and she runs so much better now. I change the oil every 3K miles and use only K&N oil filters. Before swapping to Royal Purple she was somewhat sluggish and seemed to have a slight tick in the motor coupled by a leak in the stock exhaust manifolds but since i swapped over some 20K miles ago the tick has disappeared, now to just swap over to some BBK shorty’s and get rid of the exhaust leak.


  12. I have an 02 GT with a little under 80k miles. Still using 5w-20 oil pressure is always where it should be and engine runs smooth. I use Mobil 1 when I have the money and Motorcraft when I don’t wana spend much but still want good oil. I go with a motorcraft filter or or the high-end purolator that goes for about $6 at pepboys. Those filters are right up there with Mobil 1


  13. I always use Royal Purple. Ive used it in my 97 jimmy for 22x,xxx and not a tick and the truck gets beat on real bad. I use the 5-30 in my 04 GT I like the thicker oil because its a nitrous car and see’s redline often. 70,xxx miles alot of track time and probably hundreds of spray passes later it still runs great,no burning, no leaking and no noise.


  14. Use the the same brand and viscosity of oil every time and change no matter what! Also change it according to your owner’s manual. My 09 Mustang GT recommends to change it every 7500 miles (this varies by climate/driving conditions). I choose to change mine every 6000 miles. I use Valvoline Full Synthetic 5W-20 and a Wix filter. Wix is the best filter on the market don’t buy into the K&N filter. The reason it’s a “High Performance” filter is because it uses less filtration than other filters to allow more flow, hince more performance. Not much more but a little. By the way Motorcraft Oil is made by the Ashland Oil Co. the same as Valvoline, and the Motorcraft Oil Filter is made by Wix. Use what Ford meant you to use in your Stang!


    1. Chris is right. Ford’s oil filter is a Wix, the best hands down. I take mine every 6K to the dealer who has a good price. That Ford oil is great.


  15. I use Ford Motorcraft 5W-30 and a motorcraft filter at every oil change, and my automatic 2000 GT still gets 25 mpg on the highway with almost 97,000 miles on it, no noises, no problems associated with the oil. I change it at 3,000 to 3,500 because it sees stop and go traffic from time to time, as well as several hour trips back and forth to college and my fiancees house. However, I’ve used this oil in my 1993 ford f-150 5.0 v8 as well and it had 150,000 on it when I traded it and it ran better than any that I had seen around. Go with the motorcraft, cheep, never seems to scorch or cause problems, and its recommended by the manufacturer.


  16. Technically this article is correct in the differences between synthetic and petroleum. I’ve been using Amsoil since the 80s and became a Dealer in the 90s. We haven’t made any new elements; the oils are all derived from hydrocarbons. Synthesis is using a chemical process to convert these hydrocarbons to what we want them to be. Plastic is made from hydrocarbons. The difference is where these hydrocarbons originate from. In most oils, it is refined petroleum, and in most cases of synthetic oils, this is the same, using a process called hydrocracking and forming your Group III synthetic oil (Group II is standard petroleum). Prior to around 1999 synthetics tended to be based on PAO (from natural gas) or on occasion Ester (from alcohol). PAO is considered a Group IV oil, which the die hard synthetic users consider a “true synthetic” and can withstand the extreme cold and high temps much better than the Group III synthetics, which still suffer the breakdown that petroleum does without the extra additives to help it survive. Mobil 1 and most Amsoil oils fall into this Group IV oil. Not sure on Royal Purple since I read an article a few years back in Muscle Mustangs where the RP rep stated “all synthetics come from crude” which would mean they are using Group III oil as well, since PAO and Esters do not. Prior to that they were either a blend of PAO and petroleum or full PAO in their Racing oils. Ester, BTW, falls into the Group V category, which the API has classified as “everything else.” Early synthetics in the 70s produced by Amsoil and Mobil 1 were made from esters, but they found these would tend to attract and hold moisture and weren’t the best option for street cars. For this reason they went with PAO, with Amsoil still using some esters as additives to beef their oil up more. This combination has also allowed them to formulate their oil for intervals of 25,000+ miles or one year, something they have promoted since day one. As the article said, the choice to do extended drains is up to you, but at least if you miss your “standard” change, you know you are still protected. Also the PAO based oils tend to keep the engine more clean naturally, while the Group II and III petroleum based oils rely more on additives to do the job.

    As for filters, the Amsoil Filter is probably the best on the market with an absolute efficiency of 98.7 percent on 15 microns or greater. Don’t be fooled when you read that a standard filter brags that it filters down to 2 microns or something. Look for the term “nominal” in that rating, which means it catches some particles that size. “Absolute” is from the hydraulics industry where they have to know what is captured by their filters, not what might be captured. Wix is good too, Amsoil works closely with them, but they do not make the Amsoil Filters. The media the Amsoil filters has uses nanofibers, something developed by Donaldson filters for the M1 tanks to fight the fine dust they encountered during the first Gulf War. This media is used by Donaldson in air filters and oil filters for heavy duty applications, and Amsoil uses it in their filtration media now as well. If you don’t have a good air filter, another topic, look into it. You’ll be surprised how much dust these high performance wet gauze style filters let into the engine, which shows up as silicone in oil analysis and can cause internal wear as well. Like the above poster mentioned with oil filters, they flow so well because they don’t capture that much dirt. When they do filter well, it’s because they are filling up, and then flow is less. Injen intakes recently switched their filters to the Amsoil ones to take advantage of the nanofiber flow and efficiency.

    Hope this adds a little to the article on oils and filtration to consider with whatever brand you decide on. I personally have been running with Amsoil Signature Series 0W-30 here in Florida in my 99 since I got it back in 01 along with the Amsoil Filters. Longest I’ve run has been 30,000 miles, oil analysis was still showing the oil good for continued use.


  17. I have a 07 GT I bought the car new and changed it to Royal Purple with a K&N filter at 2500 miles and have changed it at 3000 to 3500 miles every since. Inot only picked up fuel milage but also picked up power. I would reccomend this oil and filter to anyone who plans to keep their car at it’s top performance.


  18. I am also and Amsoil Dealer, Certified T-1 and Mustang GT owner, they have 2 different Synthetic engine Oil product line that woud benefit Mustang Owners.

    1. Synthetic XL 5W-30 or 10W-30 or 10W-40 provides 7500mi or 6mo change intervals.
    2. Signature Series Synthetic same weights provides 25,000mi or 1yr change intervals.
    I have an dealer website for product look-up for your vehicle.



  19. i have a 2005 mustang gt i put amsoil signature series in my stang and it was all most creepy, instantly my motor sounded different not at the tail pipe under the hood it was quite or smoother it was all most creepy. it feels like it is running stronger and smoother after 2 years i love it .


  20. Please note although some filters mentioned here are fine for your mustang they are not all the same as stated. K&n filters are very good because of what % it filters out and also size. Royal Purple Filters are so far ahead of motorcraft its not funny. Remember you get what you pay for. My friends and I always send our oil out to get analysis on how the engine is wearing. It’s the only true way of knowing.

    Still If changed properly you won’t go wrong with any oil or filters listed here.


    1. Where do you send it? I’d be interested in doing much of the same. Always good to know how your engine is wearing.


  21. Okay, just for a second, forget the 5 liter or the 4.6 modular V8 Tangs. I race enduros and these little mills made to run at 6000 RPM, we push to ten thousand. How, well I could tell you but ;-). I figured IF Royal Purple oil is the only one that will survive a whole race AND never lets the 250cc tiny mill overheat, what do you think it will do for your V8?
    I went racing an entire season in FLA (12 races) and never had to do one thing to the mill. That, my friends, is unheard of, well at least from the crowd I race with coming from all over the US. You basically stop friction in your internal combustion monster AND you will never have a “deadly” dry start again.


  22. What type of hydraulic fluid is specified for a 1967 Mustang convertible? My top won’t go down but the motor and hydraulic line are fine I’m just missing the fluid. I just don’t know what type to buy since I purchased my Mustang used and it didn’t bring the manual. Can anyone assist?


  23. I’ve got a 2008 ” Bullitt” mustang hot rod with only 8,500 miles. The motor is the Ford Racing crate 3 valve 4.6 L “hot rod” motor and cams with 10:1 compression. A little over 400hp at the flywheel. I’ve always used ford standard products during service, but recently my performance shop recommended AMSOIL telling me it is a much better product to be using in my motor. I’ve heard the pros & cons associated with standard products VS performance products, and read the info in this blog. I’m tempted to use the AMSOIL even though I’ve never heard of it before. Anyone got any thoughts on this?


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