Engine Oil Question

[203polk]

Greetings all,

I just purchased an 89 5.0. I've had it for about 2 weeks now and am planning on changing the oil. My question is what grade of oil should I get for my mustang?

The previous owner put 5 quarts of Royal Purple in it, but not sure what grade he put in. The oil filter is some brand of racing filter that none of the major or local car parts store carry. I planned I would stick with royal purple for oil and filter needs.

My question is what grade should I get living in the New England area where our weather fluctuates. Some days or weeks in the summer it's hot and dry, other time's it can be very humid and muggy. My mustang is purely a weekend driver that I take out in the noon, evening, to night time for some good ol fashioned cruising fun and meeting up with other car enthusiasts at a local donut shop parking lot.

I'm assuming that 5w30 is the preferred grade of choice? Is this correct? Also I'm not sure what internal work was done in my mustangs motor. It does have a mild cam in it, and I believe it might have been bored over to a 305. Does my selection of oil grade change? I'm looking to put an oil grade in that won't cause damage or internal break down of parts and want to car to run smoothly and operate without any issues.

Any advice and issues by those who have more foxbody knowledge than me would be greatly appreciated from this first time ford owner.

 

[rbohm]

5w-30 or 10w-30 will do just fine in your application. just use a good quality oil. i like a semi synthetic oil myself.

 

[FoxMustangLvr]

Don't over think this. Keeping all fluids fresh and full is 10x more important than dino oil vs sythetic or bottom of the shelf vs Amsoil. I use Mobil1 full synthetic 5w-xx for everything because it's good and it's priced right. I would suggest 5w-30 for you. If you don't understand what the first number (0w,5w or 10w) stands for then google it. Synthetic oil these days don't harm your seals like they used to back in the day and what the PO used to use has no bearing on what you should do for your next oil change. People think the more you spend on oil is some how magically going to prevent you from ever having to rebuild the engine which is BS.

 

[omarimoe]

Im located in CT and run my 5.0 with royal purple 10-30 and a K&N filter. So far the car has loved it and I havnt seen or noticed any issues.

 

[mikestang63]

buy whatever 10w-30 oil is on sale and a FL1A filter. Change it every 5000 miles and you will be fine. All modern oils have met the standards and have similar detergents and additives. Putting synthetic in an older engine can lead to leaky gaskets and seals.

 

[203polk]

Thanks for all the helpful insight and tips everyone. I understand oil grade and all, just wasn't sure to go with recommended stock on a built motor and if I should go with a synthetic or not cause of leakage issues I've heard of once going over to that. Will have to settle on something decent and get a good filter and change the oil in my stang this weekend.

 

[rbohm]

Thanks for all the helpful insight and tips everyone. I understand oil grade and all, just wasn't sure to go with recommended stock on a built motor and if I should go with a synthetic or not cause of leakage issues I've heard of once going over to that. Will have to settle on something decent and get a good filter and change the oil in my stang this weekend.

the leakage issue was proven to be leaks already there, just plugged up with sludge. and synthetic oils are aggressive at removing sludge, so those cars "developed" an oil leak. in reality if there is no leak, then switching to synthetic oil will not cause one.

 

[mikestang63]

the leakage issue was proven to be leaks already there, just plugged up with sludge. and synthetic oils are aggressive at removing sludge, so those cars "developed" an oil leak. in reality if there is no leak, then switching to synthetic oil will not cause one.

which is why i stated that you normally do not want to switch from dino to synthetic oil on older or high mile cars. If you are the original owner and/or know the maintenence of the vehicle, and you feel the need to spend the extra money, go for it. 99% of DD cars are fine with dino oil unless recommended by the manufacturer for synthetic.

 

[Mustang5L5]

Thanks for all the helpful insight and tips everyone. I understand oil grade and all, just wasn't sure to go with recommended stock on a built motor and if I should go with a synthetic or not cause of leakage issues I've heard of once going over to that. Will have to settle on something decent and get a good filter and change the oil in my stang this weekend.

This is a 30+ year old engine design in a production vehicle.

Run whatever oil brand you want, but really there is no need to overthink it. ANY of the oils on the market are adequate. I personally run Castrol GTX conventional and a Motorcraft Fl-1A filter in mine.

You have your guys that need to run $19/quart Synthetic Gold-dust oil or something and claim it's the best. That's fine and dandy...but my engine has run 26 years on regular oil without any issue. Why bother overthinking it.

Also, I wouldn't really call a 306 with a cam a "built" motor.

 

[203polk]

This is a 30+ year old engine design in a production vehicle.

Run whatever oil brand you want, but really there is no need to overthink it. ANY of the oils on the market are adequate. I personally run Castrol GTX conventional and a Motorcraft Fl-1A filter in mine.

You have your guys that need to run $19/quart Synthetic Gold-dust oil or something and claim it's the best. That's fine and dandy...but my engine has run 26 years on regular oil without any issue. Why bother overthinking it.

Also, I wouldn't really call a 306 with a cam a "built" motor.

Thanks I'll keep that in mind.

To clarify I never claimed I have a "built motor" I said "Also I'm not sure what internal work was done in my mustangs motor. It does have a mild cam in it, and I believe it might have been bored over to a 305". Previous owner did not disclose much info on the motor but you can tell some things have been upgraded. No claim of having a built motor from me.

 

[Mustang5L5]

Thanks just wasn't sure to go with recommended stock on a built motor and if I should go with a synthetic or not

This is where I got that from

 

[203polk]

This is where I got that from

Error on my end. Spent time on the forum reading about built motors, trying to figure how to to tell if mine is or isn't since the previous owner didn't know or inform me and only held onto the car during the winter.

 

[Shakerhood]

I run conventional 10w-30 and a FL1A in mine, as said above no need to overthink it.

 

[FoxMustangLvr]

Absolutely nothing wrong with conventional oil. I prefer synthetic these days and have had no problems running them in my old 95 4Runner that had 160k on it and my old 99 4Runner that had 130k on it. The leaked a tiny big before I switched them to Mobil1 and the leaks didn't get any worse after a few oil changes. If you have a good motor there is no problem running either and there is nothing wrong with conventional oil. I understand the science that goes into synthetic oils and I'm a firm believer in them. Read the back of the Mobil1 bottle of oil and it will tell you that it can be used in any vehicle and is safe on all of your seals. I believe it guarantees it.

Conventional = good
Synthetic = best