By the 1970s, GM began to see problems with this approach. For instance, four different North American divisions (Chevrolet, Pontiac, Oldsmobile and Buick) offered four completely different versions of a 350 in³ V8 engine - very few parts would interchange between the four designs despite their visual similarities, resulting in confusion for owners who (quite naturally) assumed that replacement parts would be usable across the board. In addition to these issues and the obvious overlap in production costs, the cost of certifying so many different engines for tightening worldwide emissions regulations threatened to become very expensive.
Thus, by the early 1980s, GM had consolidated its powertrain engineering efforts into a few distinct lines. Generally, North American and European (GM Europe) engineering units remained separate, with Australia's Holden and other global divisions borrowing designs from one or the other as needed. GM also worked out sharing agreements with other manufacturers like Isuzu and Nissan to fill certain gaps in engineering. Similarly, the company also purchased other automotive firms (like Saab Automobile and Daewoo Motor), eventually folding their engine designs into the corporate portfolio as well.
Besides GM's core business of automobiles and trucks, the company also maintained several divisions specializing in heavy-duty or industrial engines. These included Detroit Diesel, Allison, and Electro-Motive. All three produced high-capacity powerplants in a wide variety of types and sizes, most totally unrelated to the automotive divisions. GM eventually spun these divisions off to focus solely on its core business, but the engines they designed while under GM's control are included in this list to illustrate the company's level of engineering ability.
On the other hand, some of GM's earliest engine designs (from the company's 1908 founding through the 1930s) have gained colloquial nicknames over the years that have reached a level of common usage. The most famous of these may be Chevrolet's "Stovebolt" six-cylinder engine. Other names were used in a semi-formal context, like Pontiac's Silver Streak eight-cylinder (Pontiac models carrying this engine often had "Silver Streak" badges or decorations on their bodies, but the engine itself was never officially referred to as such).
There is no specific rationale for which combination of letters or numbers are used after the initial "L" digit, and it should be noted that (despite thousands of possible combinations) GM has reused many different codes over the years. This can sometimes lead to confusion, especially when engines of similar design use the same codes. (For instance, "LS6" can refer to two totally different Chevrolet V8 engines in both the older Chevrolet "big-block" family and the newer LS family.)
An example code for a specific gasoline (petrol) engine is "C20LET". In this case, "C" indicates use of a catalytic converter, "20" indicates displacement of 2.0 liters, "L" indicates a compression ratio of 8.5:1 to 9.0:1, "E" indicates use of electronic multi-point fuel injection, and "T" indicates use of a turbocharger. Codes for diesel engines are largely similar.
Holden in Australia used straight-6 engines for a number of years in their family sedan models, with local engines ranging in size from 2.15L (132ci) in the original Holden 48-215 of 1948, to the 3.3L (202ci) six used in the 1970's and 80's, up until 1985 with the VK Commodore. These engines were color-coded, often being referred to by the color of their engine block (grey, red, blue, black). These home-grown engines were replaced in the 1986 VL Commodore to coincide with new unleaded fuel requirements in Australia. Since the old engine was considered unsuitable, and a new engine hadn't been developed, the VL Commodore sported Nissan's RB30 engine, the last straight six ever used in a Commodore.
General Motors was the pioneer of V6 engines in the United States, with both the first V6 engine in an American truck (GMC models of 1960) and an American car (the Buick Special of 1961). The company later lost interest in the V6 concept, and sold the Buick design to Kaiser-Jeep in 1967. In the midst of the fuel crisis of the 1970s, GM realized that a V6 engine would be an excellent alternative to bulky inline six and V8 engines, so the company bought the design back and launched what would eventually become the familiar 3800 V6 line. From that point on, the company has continued to introduce ever more advanced designs around the world, culminating in the most recent High Feature engines.
From the 1950s through the 1970s, each GM division had its own V8 engine family. Many were shared among other divisions, but each design is most closely associated with its own division. Today, there are only two types of V8 engines still produced by GM for use in road vehicles: the Generation IV small-block and Cadillac's advanced DOHC V8, the Northstar.
Several other V12 engines, designed for use in Cadillac models, have been proposed by GM over the years but have not yet managed to reach series production.
As with the V12, Cadillac has recently considered production of a modern V16 as well, but has not gotten beyond production of prototypes and one well-regarded concept vehicle supporting the idea.
These Diesel engines were designed to fit into the engine bays of gasoline powered automobiles, but despite popular belief, they were not "converted" gasoline engines. Oldsmobile's diesel engines, the 5.7 L LF9 and 4.3 L LF7 V8s and 4.3 L LT6/LT7/LS2 V6, were notoriously unreliable, particularly in the earliest versions, though reliability had improved by the early 1980s with the advent of the DX block, along with better fuel filtering and water separators. By the early 80s,the 5.7L diesel was a fairly reliable engine with the introduction of the rollerized camshaft/roller lifter combination and had many improved enhancements that the late 70's 5.7L diesel engines did not have. Many of the reliability issues these engines developed were a combination of faults not just related to design. Many of these engines suffered major malfunctions from poor quality fuel, mechanics not properly trained in diesel repair, and even improper owner service and maintenance. Although over one million were sold between 1978 and 1985, the failure rate of GM's engines ruined the reputation of Diesel engines not just built by GM, but overall in the United States market. Eventually, a class action lawsuit resulted in an arbitration system under the supervision of the Federal Trade Commission where consumers could claim 80% of the original cost of the engine in the event of a failure.
The Oldsmobile 5.7 liter engines experienced a wide gamut of malfunctions. One of the common failures was with crankshaft bearings. This was frequently attributed to owners and maintainers running the engines on SG rated oil (intended for gasoline engines), versus CD oil (intended for Diesel engines). This prompted GM to introduce the DX block which then allowed extended oil change intervals to . D block engines required frequent oil change intervals because of the friction created between the typical flat tappet camshaft and hydraulic lifters. When the oil change interval was ignored,excessive wear was placed upon the camshaft and lifters. In 1981 when the DX block was introduced, the rollerized camshaft and roller lifters did away with any possibility of worn camshaft lobes because of reduced friction. These engines also suffered from blown head gaskets, warped heads, bad injector pumps, and bad injectors. The beginnings of these problems can be attributed to poor quality diesel fuel that may have contained water or other contaminants. These materials would damage the inside of the injector pump, and then eventually clog injectors. If water was injected into the engine or leaked in from the coolant system, it could cause a "hydrolock" which would blow head gaskets and bend valves / connecting rods because water is incompressible. Water in the fuel also causes the injectors to rust internally, affecting injection timing and causing the engine to run excessively hot, which can warp heads. This was the reason GM equipped later cars with water detectors and double filtration systems on their vehicles.
Toque-to-yield fastners - which stretch and can only be used once, but provide higher clamping force than traditional head bolts - were used to retain the Diesel cylinder heads. When a hapless owner took the vehicle in for repair, the mechanic would resurface the head, making it thinner, install a new head gasket, and then reuse the old, stretched-out fasteners. It would not be but a few thousand miles, and the vehicle was in the shop again for head gasket failure or a warped head. Nowadays high performance head bolt kits are available to do away with the problems the 5.7L diesel engines had such as the blown head gasket fiasco. Performance bolt fasteners when used within the 5.7L diesel will then make it a bulletproof, reliable design. The frustrated owner would frequently just get the shop to convert the engine to gasoline after a few repeated failures like this. As a side note, these diesel engine blocks were frequently sought by hot-rodders to build high-performance gasoline engines because of their extra heavy duty components which would withstand extreme horsepower.
Today, GM uses Diesel engines from a joint corporation between GM and Isuzu Dmax (for trucks) but offers no domestic Diesel passenger cars. General Motors' Opel division is one of the leading proponents of Diesel cars in Europe, however. In the 1970s, Opel developed the first Opel Diesel engine ever. This 2.1-litre engine made some records in a car specially built for this purpose, the Opel Rekord D (2100 cc, 60 hp). Later versions were used in the Rekord E and the Ascona B. Vehicles using these engines could be identified by a little "hill" in their hoods. Without this "hill" in the hood, the space for the engine would have been too small. Kadett D, E and Ascona B and C models also used an Opel engine (1600 cc, 54 hp). Later Isuzu engines were installed, namely for the Corsa A (1500 cc, and 1500, turbo, 67 hp) as well as for the Kadett E and Vectra A (Vectra A TD: 82 hp).
Opel today uses common rail direct injection engines designed and produced by Fiat S.p.A (MultiJet) and Isuzu (Circle L). Ownership of both designs was acquired by GM in 2005, and a new GM Powertrain Europe division in Turin, Italy (home of Fiat) was founded to manage these assets. The Fiat Diesel engine has 1900 cc, but before this cooperation, Opel had already developed two of their own engines, namely 2-litre Diesels with 82 and ; which were installed mostly in the Vectra B. GM Daewoo recently licensed two common rail designs from VM Motori.
Many of the failures and complaints GM endured have shaped the design of Diesel engines today to be quite reliable and good performing engines. Today's Diesels have excellent fuel filtration systems to minimize failures of injection systems. Many manufacturers require owners to use specific types of oils in their diesel engines, and the use of these oils must be proven for warranty claims (Volkswagen TDI). Drivers also complained of the lack of power, unpleasant noise, and the dirty, smelly exhaust from early GM diesels. Today's diesels with common-rail injection tackle all these shortcomings. They are extremely efficient, yet provide significantly more power than older diesels, and they do so with significantly less pollution and noise. Today's dealer mechanics have also undergone the proper training to service the engines properly.