The Wrong Oil?(!)

[Mrsuitcase]

Preface: I don't know much about cars (yet!)

Took my '99 V-6 to a quick lube place because I was in a hurry. I saw that the synthetic oils were "on special", so I thought - what the heck! I love this car! Time to give some love back. So I said yes to the synthetic for the first time.

Anyways, I get home and I read the invoice and it says they added 5w20. (Castrol). Anyways, I thought I remembered it was supposed to be 5w30, so I panicked. I double check my owner's manual and sure enough it says 5w30.

So, what have they done to my engine? Is this "okay" or "normal" to go to the lower weight oil because its synthetic? Or was this a mistake on their part?

Should I get another oil change immediately, or can I live with this for the next 3 months? If I live with it, should I "baby" my car? I know its only a V-6, but I love to put the pedal to the metal on my car.

Anyways, some stern advise (or reassurrances) from you fellas who are more in the know would be kindly appreciated.

Thanks for your time,

Justin
(Toronto, Canada)

 

[silver_sn95_v6]

you'll be ok for now
after working at a quick lube backk in h.s. they prolly did one of 2 things
put the wrong weight on the invoice, or they prolly only had 5w20 in synthetic and instead of losing the overhead they went ahead and put that in. i would call them and tell them they screwed up and you might get a few free oil changes out of it

 

[Lsredy2kstang]

It will be fine. It is just a little thinner but you will not see or have any effects.

i would call and tell them and maybe next oil change may be free.

 

[timeless2]

It's still cold in Canada, so the viscosity variance between 20 and 30 is minimal. Now, if you were in the Mojave desert, things would be different. That small variance could cause great harm.

 

['66 coupe]

Why do they say 5w30 for '99's, but my '01 says 5w20?

Either way, the 5w20 won't hurt. They might've looked at the computer and saw 5w20 for newer Mustangs.

 

[Mrsuitcase]

Thanks for the reassurances guys.

The last poster's question is strange though: "Why do they say 5w30 for '99's, but my '01 says 5w20?"

Don't the '99 and '01 have the same engine? The exterior is practically the same. Interesting.

 

[BlackenedSVT]

the manual says use 5w-20 becasue it will show the best economy and gas milage on the engine but a lot of other oil companies dont offer 5w-20, and instead offer 5w-30 as an alternative, that is rated at the same SAE G3raiting. Whic is fine to use.

I have used 5w-30 for the past 20,000+ milage on my car. Mobil 1 Full Synthetic.

Nothing to panic about at all.

 

[silver_sn95_v6]

5w20 was hard to find until around 2000, my 2000 6 cylinder takes 5w30, so use that,. The GT's and thos ecotec 4 bangers are 5w20 hungry, but so far as i knoe not the 6 cylinders

 

[AndyG47]

My '02 says 5W20 right on the oil cap in big yellow letters.

Maybe Ford changed it after their major mess-up of the '99 Cobras. Restrictive mufflers, bad intakes, etc. All had to be recalled. Mybe they decided to change the oil type on all mustangs afterwards, not just special production ones.

 

['66 coupe]

The differences between 10w30 & 5W20 aren't that great. As someone else pointed out, 5w20 is going to be a little more efficient. I was just wondering why there was a difference between 2000 and 2001. I'm sure the assembly process didn't change any. They're the same engines, but if Silver is right, most people didn't know what 5w20 was in 1999. Even a year ago, 5w20 was only available from Motorcraft.