Quick oil question

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dabuddha

dabuddha

Lifer
Apr 10, 2000
19,579
17
81
1998 mercury grand marquis

The owners manual says use 5w30
I've got cases of 10w30 and 5w20 in my garage. Can I substitute one of those (being lazy and don't want to make a trip to Walmart if I can help it)?

Or should I go make the trip?
This is in the DC area and its a car that's driven maybe once every couple of weeks at most (just to keep it running). Its my backup car I keep for my parents when they come to visit

TIA!
 
Jimzz

Jimzz

Diamond Member
Oct 23, 2012
4,399
190
106
You can use either. 5w20 runs very thick for its grade so its very close to 5w30 spec. And 5w30 runs think and is close to what 5w20 runs at.

You can even mix then if that helps.
 
Jimzz

Jimzz

Diamond Member
Oct 23, 2012
4,399
190
106
^

Either is fine for a NoVA winter. You can mix if worried. Again as long as the oil level is up either or a mix will be fine.

Most people over think oil.
 
M

Mark R

Diamond Member
Oct 9, 1999
8,513
16
81
In general, most car manufacturers specify a range of viscosities. Typically 2 grades above and below is usually within the range.

In the US, however, the manufactures often just specify the thinnest grade; this is because they have to specify the oil they used for their gas mileage assessments.

This is why you can have a car sold in FL where the manufacturer insists under penalty of warranty voiding that you use only 0W20, but the same car sold in Sweden, will state 5W-20, 10W30, or 15W40.
 
S

soccerballtux

Lifer
Dec 30, 2004
12,553
2
76
Mark R said:
In general, most car manufacturers specify a range of viscosities. Typically 2 grades above and below is usually within the range.

In the US, however, the manufactures often just specify the thinnest grade; this is because they have to specify the oil they used for their gas mileage assessments.

This is why you can have a car sold in FL where the manufacturer insists under penalty of warranty voiding that you use only 0W20, but the same car sold in Sweden, will state 5W-20, 10W30, or 15W40.
Click to expand...

idk about that.
I put some 5w30 in my 2008 camry engine scion tC and had horrible gas milage.
 
Meghan54

Meghan54

Lifer
Oct 18, 2009
11,684
5,228
136
Mark R said:
This is why you can have a car sold in FL where the manufacturer insists under penalty of warranty voiding that you use only 0W20, but the same car sold in Sweden, will state 5W-20, 10W30, or 15W40.
Click to expand...


What car is that, pray tell? Never heard of such crap.
 
DaTT

DaTT

Garage Moderator
Moderator
Feb 13, 2003
13,295
122
106
I used to have a car that i used 20W50....that was syrup.
 
M

Mark R

Diamond Member
Oct 9, 1999
8,513
16
81
Meghan54 said:
What car is that, pray tell? Never heard of such crap.
Click to expand...
I've seen this in Toyota and Lexus cars.

I've got a US owners manual for a 2011 IS250 in front of me. It says, ILSAC GF-4 or API SL/SM, 0W20 only. 5W20 can be used only if 0W20 is unavailable and must be replaced by 0W20 at the next oil change. With an oil change interval of 5k miles.

I've also got the lexus EU service manual maintenance summary also in front of me. For a 2011 IS250 it states ILSAC GF-4or API SL/SM 5W20 (preferred), but 5W30, 10W30 and 10W40 are acceptable. Oil change interval 10k miles.

I'm pretty sure other makes do this as well. It comes down to CAFE regulations. A lot of manufacturers have been trying every trick to get their gas mileage as good as possible for CAFE. This includes putting the thinnest oil they can get in the cars they submit for testing; the catch with this is that CAFE requires that the manufacturer make all reasonable efforts to keep the cars in the same state.

In the EU things are a bit different, and the manufacturers don't need to pull such tricks.
 
Meghan54

Meghan54

Lifer
Oct 18, 2009
11,684
5,228
136
Mark R said:
I've seen this in Toyota and Lexus cars.

I've got a US owners manual for a 2011 IS250 in front of me. It says, ILSAC GF-4 or API SL/SM, 0W20 only. 5W20 can be used only if 0W20 is unavailable and must be replaced by 0W20 at the next oil change. With an oil change interval of 5k miles.

I've also got the lexus EU service manual maintenance summary also in front of me. For a 2011 IS250 it states ILSAC GF-4or API SL/SM 5W20 (preferred), but 5W30, 10W30 and 10W40 are acceptable. Oil change interval 10k miles.

I'm pretty sure other makes do this as well. It comes down to CAFE regulations. A lot of manufacturers have been trying every trick to get their gas mileage as good as possible for CAFE. This includes putting the thinnest oil they can get in the cars they submit for testing; the catch with this is that CAFE requires that the manufacturer make all reasonable efforts to keep the cars in the same state.

In the EU things are a bit different, and the manufacturers don't need to pull such tricks.
Click to expand...



First, let me remind you of your expert, definitive declarative statement you made on the subject (relevant portion of text below):


Mark R said:
This is why you can have a car sold in FL where the manufacturer insists under penalty of warranty voiding that you use only 0W20, but the same car sold in Sweden, will state 5W-20, 10W30, or 15W40.
Click to expand...


Now, you've failed to show me that Lexus will void your warranty if you use anything other than 0W-20 in that IS250, and instead have shown me Lexus telling the owner there is an acceptable alternative to it, 5W-20.

Sort of disproved your own case.

BTW...my Lexus manual states much the same thing, 5W-30 recommended, but 10W-30 is an acceptable alternative. After all, if the listed weights in the manuals weren't acceptable and their use would void the warranty, why would Lexus even mention them in the first place?


Damn....I want to say you're just trying to read something into what's written that isn't there, but I won't. ;)
 
Meghan54

Meghan54

Lifer
Oct 18, 2009
11,684
5,228
136
Throckmorton said:
Typical for BMW
Click to expand...

From what I understand, BMW, among others, can and does require the use of synthetics exclusively. But not one weight of oil or your warranty is toast.

And that's what I was calling the BS on Mark for. He declared Lexus requires one weight of oil only, any others void the warranty, which is wrong and was proven so. (And I see he's come back to defend the position.....)


I can imagine some exotics require one weight of oil in synthetic form, but from a major manufacturer.....just have never seen it, ever.
 
M

Mark R

Diamond Member
Oct 9, 1999
8,513
16
81
It appears we have a difference in interpretation of the instructions in the manual:
"5W20 can be used only if 0W20 is unavailable and must be replaced by 0W20 at the next oil change".

To me this indicates that 5W20 is not permitted for regular or prolonged use; and that if you want to preserve your warranty your regular choice of oil is 0W20.
 
BlitzPuppet

BlitzPuppet

Platinum Member
Feb 4, 2012
2,460
7
81
I love people who customize "oil mixtures" for their engines. Bobistheoilguy.com has a bunch of these guys.

I figure that the engineers/people who designed and built the engine know better than me, and I just use what is recommended (In my case 5w-30 for all my engines) and have had no issues to date *knocks on wood*.

I use synthetic and change it myself though :).
 
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