99 Mustang V6 Oil

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This car was ran massively low on oil around 45k miles. I've been tuning it up since around then. The issue was a shop forgot to put the oil plug gasket, so it has a slight drip that will dump a liter every 2 months or so. I'm not the owner

It's now nearing 100k miles and still purrs like a kitten. Recently did seafoaming and added PCV filter to prevent the 99-2000 mustang valve cover pcv from sucking oil into the intake. It does not smoke anymore when you apply seafoam through the intake. I've also ran about 6-8 ounces of seafoam in the syn blend high mile oil that was put in maybe 1-2k miles ago.

The goal of the last change was to really clean everything out, and then run a 10,000~ OCI oil. The car isn't driven hard, it's grandma driven mostly.

What would you guys suggest? I was thinking some royal purple. After reading here long and hard though I just couldn't make up my mind. I've been a slight fan of different oils, and no I don't expect a 18%mpg increase with RP or another oil, nor do I expect it to make my tailpipe eject rainbows.

Glad to hear some unbiased opinions.
 
First welcome to BITOG!
You could of course run any 5W-20 mineral oil but if you want to upgrade to synthetic oil I'd suggest the 0W-20 grade.
If you're a fan of RP their 0W-20 is better than average.
 
My daughter owns a '99 with the V-6, I bought it for her 5 years ago. It currently has 135,000mi. on it, I think that when I bought it the odometer read somewhere around 90,000mi.

This is one of the engine families Ford back-speced to 5w-20.
I have been using 5w-20 Motorcraft since we purchased it, without issue.
It has been a fantastic car for her, shes going to school 150 mi. from home so it sits for extended tomes and then she comes home occasionally.
 
Mustang V-6's of that vintage were specifically excluded from the retroactive recommendation of other Ford engines to use XW20 weight oils. Be sure you don't follow ANY recommendation to use less than a XW30 oil in this engine.

If you want to upgrade to a synthetic oil, I would suggest, given this engine's age, Mobil 1 High Mileage oil in either the 5W30 or 10W30 weight.

I suggest using a new crush washer on the drain plug with each future oil change.
 
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Wow lots of great posts.


Originally Posted By: 1999nick
Mustang V-6's of that vintage were specifically excluded from the retroactive recommendation of other Ford engines to use XW20 weight oils. Be sure you don't follow ANY recommendation to use less than a XW30 oil in this engine.

If you want to upgrade to a synthetic oil, I would suggest, given this engine's age, Mobil 1 High Mileage oil in either the 5W30 or 10W30 weight.

I suggest using a new crush washer on the drain plug with each future oil change.


You sure? We've been running 5W20 to 5W30. In late 2000 or 2001 they changed it to 5W20 for emissions fuel efficiency purposes I've read. On the mustang sites people swear that 5W20 is only for the 2001+ which have thinner oil gasket ports, the 99 and such have larger. So if you did 5W30 on the newer v6 they say it wouldn't flow good cold? but if you run 5W20 on the 99-2000 it's same as running it on a 2001-2004. I do plan to swap this to a 4.2L 2004~ v6 from a F150 in the future, so maybe just run 5W20. This engine has some damage already, it was overreved and when you seafoam it you can hear a rod knocking around. Otherwise you never hear it, it's been like that for bout 45k miles.

New crush washer + the gasket? Nobody put a new gasket on at the oil lube places years ago so it's been leaking for bout 50k miles lol, I'll be fixing that on the next change shortly.

We've ran Syn and Syn blends over the last 50 thousand miles, I was thinking of going to RoyalP or another good syn now that we've ran seafoam in the oil so long it should be pretty clean.
 
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Originally Posted By: 1999nick
Mustang V-6's of that vintage were specifically excluded from the retroactive recommendation of other Ford engines to use XW20 weight oils. Be sure you don't follow ANY recommendation to use less than a XW30 oil in this engine.

If you want to upgrade to a synthetic oil, I would suggest, given this engine's age, Mobil 1 High Mileage oil in either the 5W30 or 10W30 weight.

I suggest using a new crush washer on the drain plug with each future oil change.


Ignore all I said above. I had forgotten that Mustangs used the 3.8 V-6 engines instead of the German-built 4.0 V-6, which was the engine excluded from the XW20 back spec.
 
Originally Posted By: 1999nick
Mustang V-6's of that vintage were specifically excluded from the retroactive recommendation of other Ford engines to use XW20 weight oils.

Like to provide some documentation to that effect?

The following is the Ford 2002 oil recommendation list.
The 3.8L V6 in the '99 Mustang is spec'd for the 5W-20 grade:

http://www.thedieselstop.com/faq/9497faq/tsb/tsb/files/020109.pdf
 
Originally Posted By: CATERHAM
Originally Posted By: 1999nick
Mustang V-6's of that vintage were specifically excluded from the retroactive recommendation of other Ford engines to use XW20 weight oils.

Like to provide some documentation to that effect?

The following is the Ford 2002 oil recommendation list.
The 3.8L V6 in the '99 Mustang is spec'd for the 5W-20 grade:

http://www.thedieselstop.com/faq/9497faq/tsb/tsb/files/020109.pdf


You were 4 minutes late, Caterham. I had already realized my error and corrected my post above.
 
Ok.
You've been tuning up for 55,000 miles.

It has an oil leak from a bad gasket for years, also. Can we figure out how to fix it? Let's think hard...

A PCV does not suck into the intake, neither does the VC. And a filter also does nothing to prevent blow by from expelling fumes/oil into the intake.

I hope the Seafoam in the intake causing smoke out the tailpipe made you feel good. Water would have been better, and cheaper -for real.

Use a 5-30 oil - anybody's.
 
I now realize I should have been more specific in my original post, my daughters '99 has the 3.8 V-6 that was back-speced to 5w-20 which I assume the OP's Mustang in question has the 3.8 also.

It was correctly posted above the German 4.0 V-6 is to use 5w-30 only, I am not sure what model years it was used in Mustangs or if it was used concurrently with the 3.8, I doubt they were offered in the same model years. The 3.8 has NO issues with 5w-20.
 
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