Fox oil change

rad4lif · May 1, 2019

i own 90 5.0 foxbody with basic upgrades i got close to 200k miles i’m running regular oil on it...my question is...i’m planning going with synthetic oil what is recommended to use n what grade...??

RaggedGT · May 1, 2019

Why the switch to synthetic?

rad4lif · May 1, 2019

RaggedGT said:
Why the switch to synthetic?

y not?...im juz asking

General karthief · May 1, 2019

If it has worked this long no need to change.

Potomus Pete · May 1, 2019

Agree, too many miles for synthetic. Probably going to leak. synthetic also cleans the inside almost like a flush (my opinion)

Blown88GT · May 1, 2019

rad4lif said:
i own 90 5.0 foxbody with basic upgrades i got close to 200k miles i’m running regular oil on it...my question is...i’m planning going with synthetic oil what is recommended to use n what grade...??

Try this

FastDriver · May 2, 2019

Too late to switch. You will create leaks you don't have as the synthetic works like a detergent. Can also dislodge sludge that could find its way to worse places. At least, this is what I've been told.

General karthief · May 2, 2019

FastDriver said:
Too late to switch. You will create leaks you don't have as the synthetic works like a detergent. Can also dislodge sludge that could find its way to worse places. At least, this is what I've been told.

@Potomus Pete read this then decide for yourself
https://auto.howstuffworks.com/switch-to-synthetic-oil.htm

CarMichael Angelo · May 2, 2019

Hmmm........maybe if I put the crude crud in my engine it won't leak then?

Mustang5L5 · May 2, 2019

I switched to synthetic a couple years ago. Nothing bad happened, and no leaks.

Mobil with a Motorcraft filter. Same viscosity as original.

1990 5.0 LX · May 2, 2019

I disagree with the comments on switching to synthetic oil. My '90 LX has 320K miles and I switched to 10w/30 Castrol synthetic at 225K miles. No smoke, no leaks. I think that's an old wives tale. At the last oil change, I switched to Mobil 15W/50 synthetic on the advice of my mechanic since it's obviously an older motor.

The argument for synthetic versus regular oil is synthetic reduces friction in the motor and increases motor lifespan. A while back in Mustangs and 5.0 magazine they had a dyno test which demonstrated that switching to synthetic added 5 hp on average at the rear wheels. That's clear proof of friction reduction.

Go with synthetic, you'll be glad you did.

Blown88GT · May 2, 2019

I tried synthetic about 25 years ago with maybe 40k miles & it leaked out everywhere, including the new supercharger.
I went to the blend a few years ago along with a seal additive. The additive did the trick. It swelled all the 30 year old seals, including the rear main seal which was replaced several times. The supercharger no longer leaks. Another seal additive in the PS pump just about eliminated the leaking.

Part of the original problem is that synthetics were only available in a much lower viscosity than what was recommended.
I remember those synthetic tests; probably have it in one of the old mags.
I replaced the engine oil, T5 oil & rear diff oil with Redline. The T5 sure shifted easier.

FastDriver · May 2, 2019

Maybe it was just true with earlier ester oils, like it says in the link that JR posted. It did actually support my understanding that it can clear deposits in the seals that open up leaks, though.

I'll tell you guys what. I happen to have recently acquired a higher mileage (at least 167k miles) car that I have relatively little $$$ in. I don't plan to keep it long, and it does not currently leak. I'll switch to Mobil 5W-30 synthetic and report back. Let's put it to the test.

Mustang5L5 · May 2, 2019

I had 100K mile or so on my Fox when I switched to Mobil 1 syn. Like I said, that was 2-3 years ago. I've driven around 1K mile since and and haven't noticed any leakage issues

1990 5.0 LX · May 2, 2019

Besides the '90 LX, here are the other older cars I'm using synthetic oil on with no smoking or leaking issues: '95 Lincoln (210K miles), '87 GMC Suburban (230K miles), '69 Galaxie (140K miles) '64 TBird (46K miles). I tend to maintain and hang onto older cars and run them as long as I can.

By the way, the '90 LX with 320K miles runs strong, no smoke, no bad noises. I think these 302s can run almost forever if they're maintained and not abused.

Black GT · Sep 4, 2019

Now you guys have me afraid to use the mobil 1 full synthetic oil I just bought for a oil change. I got the one for high mileage engines if that makes a difference. The guy I bought the car from last year told me he had just done a full synthetic oil change before I bought the car. I know the oil looked like it was fresh but wonder if he was telling the truth about full synthetic. I have no leaks at all right now.

FastDriver · Sep 4, 2019

As I referenced earlier in this thread, I switched to 0W40 Mobil 1 Synthetic in a 166k mile convertible. I put 2 thousand miles on it, and sold it last week. No leaks...
@General karthief

General karthief · Sep 4, 2019

Black GT said:
Now you guys have me afraid to use the mobil 1 full synthetic oil I just bought for a oil change. I got the one for high mileage engines if that makes a difference. The guy I bought the car from last year told me he had just done a full synthetic oil change before I bought the car. I know the oil looked like it was fresh but wonder if he was telling the truth about full synthetic. I have no leaks at all right now.

use it. Don't think too much about it. It's a little like tires, it's all in what you do with them, some tires are better in the rain, some are better on the track, they all wear out, so does oil, just change it. I stick with one brand.
I have used wolfs head synthetic blend truck oil in the 'dump truck' (7.3 turbo) for 500,000 miles, it has 585,000 on it and the only leak it has is the dipstick tube at the oil pan. Seepage at the rear main.
Never changed a valve cover gasket, only the crank seal and the oil cooler gaskets been changed.
The products today 'ain't your grandpas' oil.

90sickfox · Sep 4, 2019

The machine shop I used to deal with told me that Royal Purple may have been why my 347 lifter broke the keeper and wiped the camshaft. The drivetrain was set up correctly but I over revved. I don't know how they came up with that conclusion. Said something about how the synthetic affected the lifter.

All the racers I now at the drag strip and autox use full synthetic....usually royal purple in all their cars. I use dinosaur oil in my turbo 331...will be switching to part synthetic next oil change.

General karthief · Sep 4, 2019

FastDriver said:
As I referenced earlier in this thread, I switched to 0W40 Mobil 1 Synthetic in a 166k mile convertible. I put 2 thousand miles on it, and sold it last week. No leaks...
@General karthief

WHAT?
you want validation?
well here ya go

Fox oil change

rad4lif

Member

RaggedGT

Been here over a DECADE and still no CT

rad4lif

Member

General karthief

wonder how much it would cost to ship you a pair

Potomus Pete

I'm still waiting for the fully nude shots

Blown88GT

FastDriver

I was uncomfortably high & wearing a helmet

General karthief

wonder how much it would cost to ship you a pair

CarMichael Angelo

my rearend will smell so minty fresh,

Mustang5L5

That is…until I whipped out my Bissell

1990 5.0 LX

Member

Blown88GT

FastDriver

I was uncomfortably high & wearing a helmet

Mustang5L5

That is…until I whipped out my Bissell

1990 5.0 LX

Member

Black GT

Active Member

FastDriver

I was uncomfortably high & wearing a helmet

General karthief

wonder how much it would cost to ship you a pair

90sickfox

Wasn't a pretty sight...and I've got big hands

General karthief

wonder how much it would cost to ship you a pair

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Fox oil change

Member

Been here over a DECADE and still no CT

Member

wonder how much it would cost to ship you a pair

I'm still waiting for the fully nude shots

I was uncomfortably high & wearing a helmet

wonder how much it would cost to ship you a pair

my rearend will smell so minty fresh,

That is…until I whipped out my Bissell

Member

I was uncomfortably high & wearing a helmet

That is…until I whipped out my Bissell

Member

Active Member

I was uncomfortably high & wearing a helmet

wonder how much it would cost to ship you a pair

Wasn't a pretty sight...and I've got big hands

wonder how much it would cost to ship you a pair

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