I recently bought a 2006 Elantra GLS, and the recommended oil in the
Owner's Manual is 5W-20, with 5W-30 and 10W-30 listed as acceptable
substitutes depending upon ambient air temperatures. Now, I know all of
the previous discussions regarding the pro's and con's of each
viscosity, but I find the information on Hyundai's Service Website,
www.hmaservice.com, quite confusing, if not downright wrong.
In viewing the Shop Manual for the 2006 Elantra, a graph shows that
5W-20 is the recommended oil for ambient air temps of greater than +40
degrees C, to lower than -18 degrees C. In fact, the caption for the
bar graph for 5W-20 states: "5W-20 is recommended regardless of
environment." The graph also shows 10W-30 as being acceptable at
different ambient air temps. Strangely, it does not even list 5W-30 as
Now is where it gets interesting. In looking at the same section of the
online Shop Manual for the 2005 Elantra w/CVVT, here is what it says:
5W-20 is only recommended for ambient air temps of below -10 degrees C.
The bar graph caption includes two disclaimers: 1). Restricted by
driving condition and environment, and 2). Not recommended for
sustained high speed vehicle operation. The graph shows that 10W-30
weight oil is the best recommendation for +40 degrees C to -25 degrees
C air temp operation.
Surely, the Elantra's engine didn't change tolerances or metallurgy
between 2005 and 2006, nor did 5W-20 motor oil improve that drastically
in one year.
I've heard that the 5W-20 oil recommendation is used primarily to help
attain the government's-manadated CAFE ratings for testing by all of
the manufacturers. But, something is very strange with Hyundai's
Owner's Manual recommendation vs. their online Shop Manual data.
As an interesting observation, I have a Dodge Grand Caravan ES with
over 158K miles that's used 5W-30 its entire life with an oil change
interval of 3K or 3 Months, and it uses about a quart every 3K. On the
other hand, I also have two classic SAAB 900's, each of which has over
150K miles, and neither use any oil between changes (same change
interval). The SAABs always used 10W-30 dino oil. Is it the
difference in the oil viscosity, or just a manufacturing tolerance or
metallurgical difference - or, just coincidence?? 5W-X oils use a 5W
base stock, whereas 10W-X oils use a higher viscosity 10W base stock.
Again, any thoughts on this as well?