To keep a TH350 operating smoothly, understanding its transmission fluid capacity, fluid type, and maintenance requirements is essential. This guide provides everything you need – including a full, easy-to-reference capacity chart for all configurations.
TH350 Transmission Fluid Capacity
The TH350 transmission fluid capacity typically ranges from 4–5 quarts for a pan drop and 10–12 quarts for a full dry fill, depending on torque converter size, pan depth, and whether an auxiliary cooler is installed. Standard stock converters hold around 10–11 quarts total, while larger or high-stall converters can increase capacity to 12–14 quarts.
Deep pans also add 1–2 extra quarts.
For most maintenance services, expect to refill 4–5 quarts after changing the filter, then verify the exact level with the dipstick once the transmission is warm and idling.
| Configuration / Service Type | Capacity (Quarts) | Notes |
|---|---|---|
| TH350 – Pan Drop Only | 4.0 – 5.0 quarts | Standard drain and filter change; amount varies by pan depth. |
| TH350 – Stock Torque Converter (10”–11”) | 10.0 – 11.0 quarts | Typical factory converter fill during rebuild or transmission replacement. |
| TH350 – Large Torque Converter (12”+) | 11.0 – 12.5 quarts | High-capacity converter used in trucks or towing applications. |
| TH350 – Completely Dry Fill | 10.5 – 12.0 quarts | Includes pan, converter, and cooler lines. |
| TH350 – Aftermarket Deep Pan | 5.5 – 7.0 quarts | Deep pans add 1–2 extra quarts depending on design. |
| TH350 – With Auxiliary Transmission Cooler | +0.5 – 1.0 quart | Add capacity on top of dry fill total. |
| TH350 – High-Performance Racing Builds | 12.0 – 14.0 quarts | High-stall converters and long coolers increase total capacity. |
| TH350C Lock-Up Version – Pan Drop | 4.0 – 5.0 quarts | Same pan capacity as standard TH350. |
| TH350C Lock-Up Version – Dry Fill | 10.0 – 11.0 quarts | Similar to base TH350 but can vary slightly. |
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Overview of TH350 Transmission
The TH350 is a 3-speed automatic transmission developed jointly by Buick and Chevrolet divisions. It is a medium-duty transmission designed for small-block and big-block engines. You can find it in Chevrolet, GMC, Pontiac, Buick, Oldsmobile, and even some Jeep and custom hot rod builds.
Fluid Type for TH350
The recommended fluid for the TH350 is:
✔ Dexron III / Dexron VI Automatic Transmission Fluid
Modern Dexron VI is fully backward-compatible and offers improved oxidation resistance and smoother shifting. Many builders still prefer Dexron III-compatible fluids for classic builds.
How to Check TH350 Fluid Level
Since the exact capacity may vary based on converter size, cooler length, and pan design, always confirm the level manually:
- Warm up the transmission (10–15 min drive).
- Park on level ground.
- Shift through all gears, ending in Park.
- Check the dipstick with the engine idling.
- Add fluid slowly, ½ quart at a time.
Never rely solely on the listed capacity – always verify with the dipstick.
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TH350 Transmission Fluid Change Procedure
A standard pan drop is the most common service. Here’s how the process works:
1. Drain the Pan
The TH350 pan does not have a drain plug unless upgraded. Remove the bolts and allow fluid to fall into a catch pan.
2. Replace the Filter
The filter is a simple screen-type design. Always replace it during service.
3. Clean or Replace Gasket
Most TH350 pans use a reusable rubber gasket, but aftermarket cork gaskets are also common.
4. Reinstall the Pan
Torque bolts evenly to avoid leaks.
5. Refill with 4–5 Quarts
Start with four quarts, then check the level and add as needed.
6. Warm Up and Recheck
The torque converter will pull fluid as it circulates, so the final level must be confirmed hot.
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Common Signs Your TH350 Needs a Fluid Change
The TH350 is extremely robust, but low or old fluid can lead to failure. Watch for:
- Slow or soft shifting
- Slipping between gears
- Hard engagement with Drive
- Overheating smell
- Delayed reverse
- Dark or burnt-smelling fluid
- Foamy fluid (indicates overfill)
Changing fluid regularly can extend a TH350’s life far beyond 150,000 miles.
How Often Should You Change TH350 Transmission Fluid?
For normal driving:
✔ Every 30,000 – 40,000 miles
For towing, racing, or high-heat use:
✔ Every 15,000 – 20,000 miles
Even if the vehicle is rarely driven, fluid degrades with time, so it’s smart to refresh it every 2–3 years.
Deep Pans and Their Impact on Capacity
Many TH350 owners install a deep pan for extra cooling.
Benefits include:
- Increased fluid capacity
- Better heat dissipation
- Stronger construction
- Magnetic drain plugs (on many models)
Most deep pans increase capacity by 1–2 quarts, which is why the table shows higher values.
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Why Capacity Varies Among TH350 Builds
The TH350 has been used in dozens of vehicles for decades, including:
- Chevy Camaro
- Chevy C10
- Chevy Nova
- Pontiac Firebird
- Buick Skylark
- Oldsmobile Cutlass
- GMC trucks
- Classic hot rods
FAQs
What transmission fluid does a turbo 350 take?
A Turbo 350 (TH350) transmission uses Dexron III or Dexron VI automatic transmission fluid, with Dexron VI being the modern, fully compatible replacement that offers better heat stability and smoother shifting.
How many quarts of transmission fluid does a Chevy Express 3500 take?
A Chevy Express 3500 with an automatic transmission typically takes 11–13 quarts for a full fill, depending on the transmission model and torque converter size, though a standard pan drop usually requires 4–5 quarts.
Can I use Dexron VI in a TH350?
Yes, Dexron VI is fully backward compatible with older transmissions, including the TH350. It provides improved performance, better thermal resistance, and enhanced longevity compared to older Dexron formulations.
How much oil is in a TH350 transmission?
A TH350 transmission holds 10–12 quarts when completely dry, including the torque converter and cooler lines. A routine pan drop and filter change typically uses 4–5 quarts.
What replaced Dexron III?
Dexron VI replaced Dexron III as the current GM-approved automatic transmission fluid. It is designed to be backward-compatible with all transmissions originally specified for Dexron III.
Are TH350 and Turbo 350 the same?
Yes, the TH350 and Turbo 350 refer to the same transmission. “TH” stands for Turbo-Hydramatic, and “Turbo 350” is simply another commonly used name for the TH350.
