Shell Rotella is a good all around oil for all vehicles including scooters since it carries the JASO/MA rating as well.

JASO-MA

JASO is an acronym that stands for "The Japanese Automotive Standards Organization." Among other things, they set standards for oil to be used in motorcycles.

Shell Rotella T 15W-40 conventional oil now lists on its packaging JASO MA as one of the specifications it meets, as does the Rotella website product page:

Note that the 10W-30 conventional oil does not list JASO-MA.
The newer fully synthetic T6 5W-40 oil also lists JASO-MA compliance on its packaging and on the Rotella website.

Shell RotellaŽ T
Triple ProtectionŽ
SAE 15W-40 API CJ-4, 10W-30 API CJ-4

Shell RotellaŽ T6
Full Synthetic
SAE 5W-40 API CJ-4

Shell RotellaŽ T5
Synthetic Blend Technology
SAE 10W-40 API CJ-4,
10W-30 API CJ-4

They all meet these additional standards in 10w40 formula

API: CJ-4, SM; ACEA E9, E7;
Caterpillar ECF-3, ECF-2; Cummins
CES 20081; Mack EO-O Premium
PLUS; DDC 93K218; MAN 3275;
MTU Category 2.1; MB Approval
228.31; Volvo VDS-4; JASO DH-2


Shell Helix is probably a more common oil there to find.

Shell Helix Diesel Super
API SL/CF, ACEA A2.


Shell Helix HX7
PI SM/CF, ACEA A3/B3/B4, JASO SG+, VW 502.00/505.00, MB Sheet 229.1, BMW LL-98

Shell Helix Ultra (does not carry the diesel rating)
Meets engine test requirement of API SM, ACEA A3/B3/B4, BMW LL-01, MB Approval 229.5, VW 502 00/503.01/505 00

Shell Helix HX5
API SL/CF, ACEA A2


Castro GTX (none of their regular oils meet diesel oil standards)

SAE 5W-30:
API Service SM, SL, SJ and SH, as well as exceeding all the requirements of ILSAC GF-4/GF-3/GF-2 for PI Certified Gasoline Engine Oils and meets Energy Conserving Standards.

SAE 10W-30:
API Service SM, SL, SJ and SH as well as exceeding the requirements of ILSAC GF-4/GF-3/GF-2 for API Certified Gasoline Engine Oils and meets Energy Conserving Standards. Exceeds GM6094M.

SAE 10W-40:
API service SM, SL, SJ and SH as well as exceeding the engine protection requirements for API Certified Gasoline Engine Oils.

[SIZE=2]Castro GTX Diesel[/SIZE]
Provides protection from piston deposits, oil thickening and valve train wear while minimizing engine deposit formation.
Engineered to provide performance in engines operating under severe service conditions, including towing and hauling under high temperatures.

Applicable for on and off road heavy duty 4 stroke trucks, gasoline and diesel light trucks and passenger cars where API CI-4, CH-4, CG-4, CF-4, CF SL or SL SJ are recommended

Special viscosity improvers, anti-wear, anti-oxidant and detergent additives protect and maintain cleanliness in hot running, heavy duty diesel and heavy duty gasoline engines.

Approved against the Mack EO-M and EO-M+ specifications and meets the performance requirements of Cummins CES 20071,72,76 specifications. Recommended for Mack, Cummins, Caterpillar, Navistar and Detroit Diesel 4 stroke engines where API CI-4, CH-4 or CG-4 is required.

Recommended for applications calling for Volvo VDS, VDS-2 and API service CI-4, CH-4, CG-4, CF-4, CF/SI, SJ.


Castro Edge
ILSAC GF-5, GF-4 and GF-3 and/or API SN, SM and SL

Castrol SYNTEC is now Castrol EDGE with SYNTEC Power Technology.
ILSAC GF-5, GF-4 and GF-3 and/or API SN, SM and SL

Castrol GTX High Mileage
API SN, SM and SL
[SIZE=5]

Just because it's the right weight oil does not mean it's the right oil for your vehicle. You got to read the API rating.[/SIZE]