the skinny about oil weight?
 

Here is a question that boggles my mind. From everything I've heard about oil weight, 10W30 seems to be the sweet spot, yet scion recommends 5w30.
Is there any reason for this? correction: is there any GOOD reason for this?

Re: the skinny about oil weight?
 

A little better MPG; a little better cold weather starting. The main reason is that to get EPA rating of whatever MPG they list on the sticker, they use 5w30, so they have to recommend that weight. (At least, that's MY understanding of the situation.)

Actually, there is a TSB that recommends 5w-20 on 2006 and up. Like pooder said, it's for cold weather starting and better mileage. I got between 1-3 MPG increase (as indicated on my ScanGuage) after switching from 5w-30 to 5w-20. In southern FL, don't think you need to worry about it. You could probably even use straight 30 weight.

i use 10w-30 and get 33-35mpg

FYI - that is NOT for the xB's. Do NOT use 5w20 if you are still under warranty as it will be voided.

5w30 is a fantastic oil in modern engines.

but then another question comes to mind, how does oil weight effect gas milage?

In a nutshell, thinner oil = easier flow= better MPG. But this comes at a cost....engine protection.

The difference between a 5w30 and 5w20 is not going to amount to more than a 1 MPG increase....probably closer to a .2 MPG increase.

Stick with what is called for in your owners manual.

"5w20 oil is a lighter viscosity than a 5w30 oil and therefore has less internal engine frictional losses, or less drag on the crankshaft, pistons and valve-train. This decrease in frictional power loss promotes increased fuel economy. This increased fuel economy is virtually undetectable to the average consumer without the use of specialized engine monitoring and testing equipment when compared to a 5w30, 10w30 or a 0w30 viscosity motor oil."

"Question: What are the negative aspects of using a 5w20 oil?

Answer: 5w20 oil has less film and shear strength than a 5w30, 10w30 or a 0w30 motor oil. This can lead to increased engine wear under today's demanding heat and high-stress engine performance conditions."

Umm... At least try reading the TSB (EG018-06) before you tell people it'll void the warranty. Because if bought a 2006 made after Feb or you're getting your oil changed at the Toyota dealer, you should have 5w-20 in it.

Toyota Motor Corporation manufacturing plants have begun using ILSAC GF–4 engine
oil. This engine oil is recommended due to its superiority in terms of fuel economy and
engine protection and due to its benefits for both the customer and the environment.
ILSAC GF–4 can be used in all Toyota and Scion engines.

ILSAC GF–4 SAE 5W–20
This oil has been set as the Toyota genuine engine oil, starting in February 2006 for
the U.S. This oil is superior in terms of fuel economy, engine protection, and cold
starting performance.

Engines That Can Use 5W–20 and 0W–20:
ILSAC GF–4 SAE 5W–20
AZ series
GR series
JZ series
MZ series
NZ series
RZ series
UZ series
VZ series
1ZZ–FE
2TR–FE

ILSAC GF–4 SAE 0W–20
(Beginning with 2006 MY)
2AZ–FE Camry
2AZ–FE Solara
2AZ–FE Highlander
2AZ–FE RAV4 (ACA3#)

Not sure if it is true or not, but I hear a *rumor* (you know how that goes) that the switch was due to problematic sludging they've been having in some motors (such as the older 3.0L V6's) and that *-20 helps to prevent it.

Amsoil propaganda. Probably from before they had a 5w-20. But I don't know why they still have this info posted when they now sell a 5w-20.
http://bestsyntheticoil.com/dealers/...w20-cafe.shtml

Yep, probably the sludge settlements and the fuel economy. 1 MPG increase isn't much to the consumer, but it's something to Toyota if they can get a better CAFE rating with a simple oil spec change.

Toyota isn't the first or only one to do this. Honda has specified 5w-20 for a few years. I think Ford does for some their vehicles too.

Personally, I'd stick to manufacturer recommendations to avoid warranty issues.

dang, thanks guys, guess next tune up I'll get 5w30, didn't think it effected it that much.

As stated in the TSB, "Use the recommended grade specified on the oil filler cap or in the Repair Manual or Owner’s Manual for each vehicle."

I emailed Scion directly. Here is the response:

------------------------------------------------------------------------------------

From: Scion [scion_mail@scion.com]
Sent: Wednesday, January 17, 2007 1:34 PM
To:
Subject: Service/Maintenance > Fluids > Engine Oil[Incident: 070114-000748]
Recently you contacted Scion Customer Experience. Below is a summary of your contact message and our response.



Subject
Service/Maintenance > Fluids > Engine Oil

Discussion Thread
Response (Mike H) 12/17/2006 01:33 PM
Thank you for contacting Scion.




We appreciate the opportunity to address your inquiry.


No, 5w30 is the recommended oil weight for your 2006 Scion xB as specified in your owners manual. Use of any other weight can void your warranty.






Please feel free to contact us should you have any further questions or comments. We would be happy to assist you. You may contact us directly at 1-866-70-SCION or by email at Contact Us.



Thank you for your interest in Scion.



Scion Customer Experience

I guess it is really up to each individual user. I cant really say how much of a difference it is really going to make between the 30 and 20 weights, but I am going with what was recommended to me fro mScion since I have the paperwork to back up my use of 5w30 if any problems should arise.

edit

I use 5w-20 in my '06 tC (Built Feb. 2006). The cap says 5w-30, I use 5w-20. The engine sounds fine, it has not blown up and will not blow up.

waiting on a used oil analysis I sent out on my fill of pennzoil platinum 5w-20 to prove everything is fine.

Can you let me know how that UOA turns out?
Im curious as to PP's numbers as I made the switch to PP from M1.