• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

5W20 or 5W30

  • Thread starter Thread starter rickshaw
  • Start date Start date Jan 25, 2009
R

rickshaw

Member
Jan 6, 2009
53
0
6
Vilano Beach, FL
Jan 25, 2009
#1
  • Jan 25, 2009
  • #1
Newbie here ready to change the oil in my 02, that has 50K miles and the previous owner did the quick lube method of cheap oil.

I'm a synthetic guy and wonder how much difference there is between the different oil viscocities. Anybody using 5w30? It's plenty warm in FL do that should not be a problem.

And any thoughts on a flush before the change?
 

SVT32VDOHC

waiting for the next hack atta
Founding Member
Nov 22, 2001
3,501
28
119
Motor City
Jan 25, 2009
#2
  • Jan 25, 2009
  • #2
Use what the sticker under the hood recommends. Don't play around with different weights with MOD motors.

Don't flush the motor either. That just takes any crap inside and puts it somehwere else...like your oil pump...then your motor could go bad.
 

evil281

New Member
Jan 6, 2008
276
0
0
Arizona
Jan 25, 2009
#3
  • Jan 25, 2009
  • #3
i use 5w30 and my car runs great
 
R

rickshaw

Member
Jan 6, 2009
53
0
6
Vilano Beach, FL
Jan 26, 2009
#4
  • Jan 26, 2009
  • #4
thanks for the feedback. i accidently used a different weight in my truck and the oil pressure went very high at WOT.

the reason i asked was Costco is selling a Mobile 1 6 pack of 5w30 for $35.00. OK, so I'm cheap.
 
T

ThunderHorse

New Member
May 25, 2008
26
0
0
Jan 26, 2009
#5
  • Jan 26, 2009
  • #5
My owners manual says to use motorcraft 5w20 full synthetic. However I use the Mobil 1 5w20 because there is no difference to me and mobil 1 is easier to get where I live. I have used 5w30 mobil 1 in the past and had no problems with it.
 

SVT32VDOHC

waiting for the next hack atta
Founding Member
Nov 22, 2001
3,501
28
119
Motor City
Jan 26, 2009
#6
  • Jan 26, 2009
  • #6
99-00 Mustang GT's ask for 5w30. 01-04 Mustang GT's ask for 5W20.

Waaaaay back in the day, there was a thread here or somewhere else about a guy with a 99 Cobra/01 Cobra who used 10w30 in the car because he was "hard" on it. Well the dealer proved it starved the heads from oil and proved the oil was in fact 10w30. They voided his warrenty.

Since then, I use what Ford says.
 

Gearbanger 101

Straight Outta Locash
20+ Year Stangneter
Aug 10, 2002
9,457
1,377
234
Ontario, Canada
Jan 26, 2009
#7
  • Jan 26, 2009
  • #7
SVT32VDOHC said:
99-00 Mustang GT's ask for 5w30. 01-04 Mustang GT's ask for 5W20.
Click to expand...
And the best part about it is, is there's not a damn bit of difference in the tolerances of the engines. In all honesty, Ford probably went with the 5W20 synthetic because they likely buy it cheaper in bulk....and putting the word synthetic in front of it allowed them to move oil change intervals from 5,000km to 8,000-10,000km between changes.

SVT32VDOHC said:
Waaaaay back in the day, there was a thread here or somewhere else about a guy with a 99 Cobra/01 Cobra who used 10w30 in the car because he was "hard" on it. Well the dealer proved it starved the heads from oil and proved the oil was in fact 10w30. They voided his warrenty.

Since then, I use what Ford says.
Click to expand...

I would love to see how they "proved" that. My guess is that they fed him whatever they thought he needed to hear in order to not have to cover the warranty claim. After working for a Dealership for 4-years, I can tell you first hand they'll try whatever they can to get out of warranty work.

As far as oil goes....I stick with 5W30 in mine....dino...synthetic...its all the same. If I run synthetic in it, I wait a little longer between changes. Then again, I don't seem to fill my oil separator as often with the dino oil, so that's what I've been sticking with. Not to mention with the dino oil you change your filter twice in 10,000km, where with the synthetic oil you're more likely to only change it one. And in the end....its the quality and condition of your oil filter that’s the most important....not the type of oil you're running.
 

tag4car

Member
Nov 21, 2005
0
0
16
Birmingham AL
Jan 26, 2009
#8
  • Jan 26, 2009
  • #8
^ i remember hearing something about the CAFE rating
 

SVT32VDOHC

waiting for the next hack atta
Founding Member
Nov 22, 2001
3,501
28
119
Motor City
Jan 26, 2009
#9
  • Jan 26, 2009
  • #9
Gearbanger 101 said:
And the best part about it is, is there's not a damn bit of difference in the tolerances of the engines. In all honesty, Ford probably went with the 5W20 synthetic because they likely buy it cheaper in bulk....and putting the word synthetic in front of it allowed them to move oil change intervals from 5,000km to 8,000-10,000km between changes.

I would love to see how they "proved" that. My guess is that they fed him whatever they thought he needed to hear in order to not have to cover the warranty claim. After working for a Dealership for 4-years, I can tell you first hand they'll try whatever they can to get out of warranty work.

As far as oil goes....I stick with 5W30 in mine....dino...synthetic...its all the same. If I run synthetic in it, I wait a little longer between changes. Then again, I don't seem to fill my oil separator as often with the dino oil, so that's what I've been sticking with. Not to mention with the dino oil you change your filter twice in 10,000km, where with the synthetic oil you're more likely to only change it one. And in the end....its the quality and condition of your oil filter that’s the most important....not the type of oil you're running.
Click to expand...

I agree. The dealer will do whatever they can to get money. I just remember the thread. Here at work, we put whatever oil is on sale in your trucks..lol. We never have problems.

As far as my Mustangs though. I put what is recommended.

96 Cobra...(even with the Vortech) gets conventional 5w30. No synthetic for me.

04 Cobra...haven't done an oil change yet since I just bought it. It will get the required 5w20. Don't know if I'll go with synthetic yet. It has 5,700 miles. If I do go synthetic, it is going to be Ford Motorcraft brand. That is a blend. I used that in my 04 F150 lease truck and it seemed fine.
 

mrvax

Stay thirsty my friends
Founding Member
Nov 29, 1999
5,225
3
79
SN Moderator: Orlando, Fl.
Jan 26, 2009
#10
  • Jan 26, 2009
  • #10
If I'm not mistaken, there was no engine change between 99 & 00 when the viscosity changed. I believe the thinner oil got a wee bit better gas mileage.

So, if you have a warantee, go with the "official" brand for your year.
No warantee? Then use the 5w-30 that was designed for use in the mod motor.

BTW: When my Mustang hit 100,000 miles I switched to full synthetic. I could tell a difference.
 
You must log in or register to reply here.

Similar threads

A
2001 Mustang GT, scorched metal smell and noise from trans/diff?
  • AndyE2255
  • Dec 1, 2025
  • SN95 4.6L Mustang Tech
Replies
4
Views
416
SN95 4.6L Mustang Tech Dec 28, 2025
gkomo
Place to Avoid: Jamison Auto Group in Gulfport, MS
  • D Durden
  • Oct 20, 2025
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • 2 3
Replies
45
Views
2K
1965 - 1973 Classic Mustangs -General/Talk- Feb 4, 2026
nickyb
C
Progress Thread 2004 Comp Orange GT
  • ctandc
  • Jun 26, 2023
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • 2 3
Replies
56
Views
4K
1996 - 2004 SN95 Mustang -General/Talk- Jun 1, 2026
ctandc
C
SOLD [Minnesota] 2014 Ford Mustang GT | Grabber Blue | 6MT Coupe
  • Mycelus
  • Mar 20, 2023
  • S197 Mustangs For Sale (2005-14)
Replies
1
Views
6K
S197 Mustangs For Sale (2005-14) Mar 27, 2023
Mycelus
Engine Rocker Noise after Aluminum heads and 1 piece CM Pushrods
  • 79pace
  • Apr 12, 2022
  • Fox 5.0 Mustang Tech
Replies
17
Views
4K
Fox 5.0 Mustang Tech Apr 19, 2022
Monkeybutt2000
M
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?