Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance How long does synthetic oil last?

I was checking out the api site, and noticed amsoil only has API certification of the following oils:

http://eolcs.api.org/DisplayLicenseInfo.asp?LicenseNo=0995

AMSOIL PCO 15W-40 CI-4/SL
AMSOIL XL-7500 10W-30 SL*
AMSOIL XL-7500 10W-40 SL
AMSOIL XL-7500 5W-20 SL*
AMSOIL XL-7500 5W-30 SL*
* energy conserving

Why do so few of there oils carry API certifications?

For comparison, all of mobils oils are certified:

MOBIL 1 0W-20 SL/CF*
MOBIL 1 0W-30 SL/CF*
MOBIL 1 0W-40 SL/CF*
MOBIL 1 10W-30 SL/CF*
MOBIL 1 15W-50 SL/CF
MOBIL 1 5W-30 SL/CF*
MOBIL DELVAC 1 5W-40 CF,CF-4,CG-4,CH-4,CI-4/SL
MOBIL DELVAC 1300 SUPER 10W-30 CF,CF-4,CG-4,CH-4,CI-4/SJ
MOBIL DELVAC 1300 SUPER 10W-30 CF,CF-4,CG-4,CH-4,CI-4/SL
MOBIL DELVAC 1300 SUPER 15W-40 CF,CF-4,CG-4,CH-4,CI-4/SL
MOBIL DELVAC 1310 10W CF
MOBIL DELVAC 1330 30 CF
MOBIL DELVAC 1340 40 CF
MOBIL DELVAC 1350 50 CF
MOBIL DELVAC 1630 30 CF
MOBIL DELVAC 1640 40 CF
MOBIL DELVAC 1650 50 CF
MOBIL DRIVE CLEAN 10W-30 SL*
MOBIL DRIVE CLEAN 10W-40 SL
MOBIL DRIVE CLEAN 20W-50 SL
MOBIL DRIVE CLEAN 5W-20 SL*
MOBIL DRIVE CLEAN 5W-30 SL*
MOBIL DRIVE CLEAN BLEND 10W-30 SL/CF*
MOBIL DRIVE CLEAN BLEND 5W-30 SL/CF*
MOBIL DRIVE CLEAN HD 30 SL
MOBIL DRIVE CLEAN HD 40 SL
MOBIL DRIVE CLEAN PLUS 5W-30 SL/CF*
MOBIL DRIVE CLEAN PLUS HM 10W-30 SL/CF
MOBIL DRIVE CLEAN PLUS HM 10W-40 SL/CF
ESSO UNIFLO 10W-30 SL*
ESSO UNIFLO 10W-40 SL*
EXXON XD-3 10W-30 CF,CF-4,CG-4,CH-4,CI-4/SL
EXXON XD-3 15W-40 CF,CF-4,CG-4,CH-4,CI-4/SL
EXXON XD-3 20 CF
EXXON XD-3 30 CF,CF-2
EXXON XD-3 40 CF,CF-2
EXXON XD-3 50 CF,CF-2
EXXON XD-3 ELITE 15W-40 CF,CF-4,CG-4,CH-4,CI-4/SL
EXXON XD-3 EXTRA 15W-40 CF,CF-4,CG-4,CH-4,CI-4/SL
SUPERFLO 10W-30 SL*
SUPERFLO 10W-40 SL*
SUPERFLO 20W-50 SL
SUPERFLO 30 SL
SUPERFLO 40 SL
SUPERFLO 5W-20 SL*
SUPERFLO 5W-30 SL*