The 2013 GMC Sierra range offers great flexibility for buyers, with engines ranging from a basic but sturdy V6 workhorse, to a range of potent V8s, including a standout 5.3-liter, and even a Hybrid model that delivers class-leading fuel economy.
Key Points
- The 2013 GMC Sierra 1500 is available with five different engine options: 4.3L V6, 4.8L flex-fuel V8, 5.3L flex-fuel V8, two 6.2L V8s, and a 6.0L V8 hybrid.
- The 4.3L Work Truck models may feature strong cast iron engine construction, but they’re seriously lacking in power.
- A choice of iron or aluminum blocks are available for 5.3L engines, and both deliver impressive fuel economy and the range’s most advanced engine tech.
- The 6.2-liter models tow up to 10,700 pounds when equipped with the Max Trailering Package. However, this isn’t enough to match the Ford F-150’s towing ability.
- Sierra Hybrid models may deliver an impressive 23 mpg on the highway, but poor payload and weaker towing capacities are the price you pay for it.
Base 4.3L V6 is an Underwhelming Engine for a Work Truck Like the 2013 GMC Sierra
The 2013 model was the final year for the third-generation GMC Sierra, and the truck’s dated base engine was a clear sign of its age. The only option with fewer than eight cylinders, the 4.3-liter V6 doesn’t exactly offer the power you’d expect in a workhorse like this.
A mere 195 hp at 4,600 rpm and 260 lb.-ft. of torque at 2,800 rpm is on offer from this asthmatic engine, making it seriously underpowered for towing or hauling heavy loads.
But it at least makes that torque lower in the rev range than any other engine, which is likely why it is primarily aimed at base Work Truck variants.
It also only comes paired with an old-school four-speed automatic transmission. As with all models, it’s available with both rear- or four-wheel drive.
Indicating its age, this engine still utilizes strong cast iron construction and is the only one in the range to use a distributor rather than individual ignition coils. It uses a pushrod valvetrain like all other engines in the range, but it’s the only one to lack variable valve timing.
Disappointingly, the 4.3 only achieves 15/20/17 mpg on the city/highway/combined test cycles, meaning it’s less efficient than the much more powerful 5.3-liter V8. Four-wheel drive models see efficiency drop to 14/18/16 mpg.
Servicing is recommended every 7,500 miles for the Sierra, although Kelley Blue Book notes it can be extended to 12,000 miles when driven in optimal conditions thanks to its oil life monitor system.
The Sierra requires 4.5 quarts of fully synthetic oil, either 5W-30 or 0W-30 for colder climates.
2013 GMC Sierra’s 4.8L Engine Ups the Power, but You’ll Pay the Price for it at the Pump
The entry-level V8 in the 2013 GMC Sierra range is a 4.8-liter unit that is a step up from the base V6.
With an aluminum cylinder head and variable valve timing, the engine makes a much healthier 302 hp at 5,600 rpm and 305 lb.-ft. at 4,600 rpm.
The four-speed auto remains, however.
While power is up, there is a big price to be paid for it at the gas pump, however. Despite its position in the range, the 4.8-liter is the second-least efficient on offer.
Fuel economy is rated at 14/19/16 mpg city/highway/combined for rear-wheel-drive models; four-wheel drive sees it manage just 13/18/15 mpg.
The 4.8-liter engine, like most V8 options, does offer Flex Fuel compatibility for those wanting to use greener E85 gas.
Be warned, though: Fuel economy will drop even further to just 11-12 mpg combined when running on it.
For all V8 models including the 4.8, oil changes require 6.0 quarts of fully synthetic 5W-30 or 0W-30 oil.
5.3L GMC Sierras Feature Iron and Aluminum Block Options, Along with Cylinder Deactivation
Like the 2013 Chevrolet Silverado it shares a platform with, the GMC Sierra 1500 offers two almost-identical 5.3-liter V8 engines.
Both engines produce an identical 315 hp at 5,200 rpm and 335 lb.-ft. at 4,000 rpm. Each is also paired to a six-speed automatic transmission.
The sole difference between the two is, the “LMG” engine fitted to lower-trim trucks utilizes a cast iron block for increased strength and durability, while “LC9” engines fitted to higher-trim models use an aluminum block.
Regardless, both feature GM’s Active Fuel Management cylinder deactivation system to help save on fuel, which clearly does the trick.
At 15/22/18 mpg city/highway/combined for rear-wheel-drive models and 15/21/17 mpg for four-wheel-drive models, it’s the most efficient non-hybrid engine on offer.
Both versions are also E85 compatible, delivering 13 mpg combined when running on ethanol.
Range-topping 6.2L V8 Gives the 2013 GMC Sierra a 10,700-pound Towing Capacity
The all-aluminum 6.2-liter V8 is the most powerful engine in the range, and the best option for anyone wanting to use their Sierra to tow or haul heavy loads.
Boasting 10,700 lbs. of maximum towing capacity, it leads the range in that metric. However, the 2013 Ford F-150 can tow more, with some models rated up to 11,300 lbs.
Regardless, the 6.2 will tow what it can with ease thanks to its impressive outputs of 403 hp at 5,700 rpm and 417 lb.-ft. at 4,300 rpm. That power is enough to get it from 0-60 mph in an impressive 5.8 seconds.
Fuel economy is poor, though, given this engine’s size and power. Expect just 13/18/14 mpg city/highway/combined at best, and do note that premium gas is recommended but not required. Running on E85, you’ll be lucky to get 11 mpg combined.
2013 GMC Sierra 1500 Hybrid Achieves 21 mpg Even with a V8 Heart
As a way to help the 2013 Sierra achieve class-leading fuel economy, GMC also offered a Hybrid version. It’s a unique powertrain for a vehicle of the time, pairing a 6.0-liter V8 with two electric motors that drive the wheels through a special electrically variable transmission.
The blended four-speed gearbox with a CVT improves drivability but crucially affects fuel economy, with it able to keep the V8 at an optimal engine speed at all times.
A small 300-volt NiMH battery pack also helps it drive on electric power alone at times.
Power is rated at 332 hp at 5,100 rpm and 367 lb.-ft. at 4,100 rpm for the 2013 GMC Sierra Hybrid.
However, despite those healthy outputs, the added weight limited its payload and towing capacities to just 1,527 lbs. and 6,100 lbs., respectively.
Impressive fuel economy comes through with EPA-rated estimates of 20/23/21 mpg city/highway/combined.
Although it doesn’t offer Flex Fuel compatibility like other V8 Sierras, the engine does feature AFM cylinder deactivation tech.
5.3L V8 is an Obvious Choice for 2013 GMC Sierra 1500 Buyers
If there’s one engine option that raises itself above the rest of the 2013 Sierra’s offerings, it’s the 5.3-liter V8.
Whether it’s an iron-block or aluminum-block model, the 5.3 offers impressive gas mileage thanks to its many fuel-saving features, and offers the best blend of performance and capability.
The 6.2-liter engine may be a worthwhile upgrade for drivers who tow on a regular basis. But for most buyers, the 5.3L Sierra is the way to go.
Photos: GMC
