The name – reflecting a "Series 90" fitted with an 8-cylinder engine – first appeared in 1941 and was used again after American consumer automobile production resumed post-World War II.

This left the two remaining number-names to carry on into the 1990s as the bread and butter of the full-size Oldsmobile lineup until the Eighty Eight-based Regency replaced the 98 in 1997.

Technical features included electro hardened pistons, full pressure lubrication and automatic choke with fast idle mode.

Standard 98 equipment included safety glass, spare wheel and tire, dual horns, vacuum booster pump, cigarette lighter, and a solenoid starter system.

Standard equipment on 98s included a solenoid starter, fender skirts, E-Z-l rearview mirror, and foam rubber seat cushions.

Available in four special Holiday colors, as well as four two-tone combinations, it was priced the same as the convertible, and was similarly equipped, with hydraulically operated windows and seat.

Standard equipment on the three body styles included bumper guards, gray rubber floor mats front and rear, electric clock, dual horns, aluminum door sill plates, chrome gravel guards, foam rubber seat cushions, turn signals, carpeting front and rear, stainless steel wheel trim rings, windshield washer, and Deluxe steering wheel with horn ring.

New in 1953, the Fiesta joined the Cadillac Series 62 Eldorado and Buick Roadmaster Skylark as top-of-the-line, limited-production specialty convertibles introduced that year by General Motors to promote its design leadership.

Standard equipment for 1953 included bumper guards, electric clock, lined trunk, dual horns, cigarette lighter, chrome moldings, twin interior sun visors, rear seat robe rails, special rear stainless steel trim, chrome window ventiplanes, windshield washer, and Deluxe steering wheel with horn ring.

Standard Ninety-Eight equipment included bumper guards, rubber simulated carpets front and rear, electric clock, lined trunk, dual horns, cigarette lighter, aluminum door sill plates, turn signals, chrome rocker panel moldings, deck lid ornament, foam rubber seat cushions, padded dash,[3] parking brake light, courtesy light package, stainless steel wheel discs, windshield washer, and deluxe steering wheel with horn ring.

Standard equipment included turn signals, bumper guards, stainless steel moldings, dual horns, cigarette lighter, front and rear floor mats, inside rearview mirror, foam rubber seat cushions, stainless steel rocker panel moldings, front seatback robe cord, spun glass hood insulation, rear window ventiplanes, electric clock, stainless steel wheel discs, custom cushion lounge seats front and rear, hand brake light, courtesy light package, padded dash, Deluxe steering wheel with horn ring, and windshield washer.

Standard equipment included armrests, bumper guards, lined trunk, rotary door latches, dual horns, cigarette lighter, turn signals, rubber floor mats, aluminum door sill plates, sun visors, front and rear carpeting, foam rubber seat cushions, courtesy lights, front fender medallions, deck lid "Ninety-Eight " script, back-up light moldings, electric clock, Jetaway Hydramatic Drive, padded dash, power steering, windshield washers and Deluxe steering wheel.

[14] Standard equipment included armrests, turn signals, rubber floor mats, sun visors, front fender chrome script, exposed chrome roof bows, side interior courtesy lights, electric windows,[3] special emblems, power steering, power brakes, and Jetaway Hydramatic.

Standard series equipment included four headlights, oil filter, turn signals, printed circuit instrument cluster, aluminum anodized grille, padded dash, foam rubber padded seat cushions, courtesy lights, parking brake light, special side moldings, chrome rocker panel moldings, Jetaway Hydramatic transmission, power steering and brakes, dual exhaust, electric clock, color accented wheel discs, and chrome wheel frames.

Standard equipment included die-cast grille, deep pile carpeting, 21-gallon fuel tank, full-flow oil filter, foam seat cushions, foot-operated parking brake, two-speed windshield wipers, special molding package, Deluxe steering wheel, map light, heavy duty air cleaner, courtesy lights, Roto Hydramatic, power brakes, power steering, special rocker panel moldings, self-regulating electric clock, dual rear seat cigarette lighters and special headliner.

Standard equipment included: Roto Hydramatic; power steering, brakes, windows and seats; windshield washer; special wheel discs; clock; courtesy and map lights and padded dash.

The 1965 Ninety-Eight was completely redesigned from the ground up along with other full-sized General Motors cars but retained the larger C-body shared with Cadillac and Buick Electra in contrast with the B-body used in the Oldsmobile 88.

Standard equipment included automatic transmission, power steering and brakes, power windows, clock, padded dash, foam padded seats, parking brake light, Deluxe steering wheel, special wheel covers, windshield washer and two-speed electric wipers, courtesy and glovebox lamps, and front seat belts.

The standard 455 cubic-inch Rocket V8 was rated at 320 hp (239 kW) and designed to run on lower octane regular lead, low-lead or unleaded gasoline for the first time this year thanks to a General Motors-mandate that all engines be designed to run on such fuels in preparation for the catalytic converter equipped cars of 1975 and later years that absolutely required unleaded gasoline.

Standard equipment included: Deluxe armrests, dual ashtrays, power brakes with front discs, cigarette lighter, carpeting, inside hood release, dome light, molding package, windshield radio antenna, foam sheet cushions, power steering, Deluxe steering wheel, Turbo-Hydramatic transmission and wheel opening covers.

The federal 5 mph (8.0 km/h) impact standard was rolled back for 1984, prompting GM to make major changes to the bumpers to save weight; predictably, this drastically reduced their effectiveness.

This car featured plush "Prima" velour seats with embroidered emblems, cut pile carpeting, and electroluminescent opera lamps on the B-pillars.

Anti-lock brakes became optional for 1986 and a "Grande" package was offered in 1986 and 1987 with composite headlights and specific front end panel (1986 only), and 45/45 leather seats with pigskin inserts and console with a combination lock.

[citation needed] With a base price of just over $24,000 USD (equivalent to $64,700 in 2023), the Touring Sedan cost roughly 30% more than the most expensive other trim levels of the Ninety Eight.

[30][32] Externally the Touring Sedan used cloisonné badges on the hood, C pillars and rear quarter panel[30][32] and the lower body featured model-specific dark gray cladding and fog lamps.

[30][32] The Touring Sedan featured burl walnut veneer accents and twin bucket seats by Lear Siegler with 16-way power adjustments.

[32] In 1988, a power pull-down trunk lid and an onboard computer with oil life monitor (marketed as the "Driver Information System") became optional for all Ninety-Eights.

The wheelbase remained unchanged from the previous generation, and overall length increased by over 9 inches (229 mm), mostly at the rear of the car, resulting in a larger trunk.

[30] The two-tone body of the previous generation was replaced with a monochromatic exterior (including a body-color grille); all chrome trim was deleted (with the exception of badging).

In 1993, a new value priced Special Edition model was added to the lineup and Ninety-Eight received an improved 3.8 L V6 engine offering better performance and fuel efficiency.