Change the Oil on Your John Deere S100 in 15 Minutes

The John Deere S100 series uses Briggs & Stratton engines that need regular oil changes to stay reliable. Fresh oil every 50 hours keeps the engine running cool and prevents premature wear. For a deeper look at engine oil options, see our small engine oil guide. This guide covers the complete oil change process for S100, S120 and S130 models.

S100 Oil Specifications

The S100 series uses Briggs & Stratton single-cylinder engines.

Oil Type and Capacity

Model	Engine	Oil Capacity	Oil Type
S100	B&S 17.5 HP	48 oz (1.5 qt)	10W-30
S120	B&S 19 HP	48 oz (1.5 qt)	10W-30
S130	B&S 22 HP	48 oz (1.5 qt)	10W-30

Temperature Considerations

Temperature Range	Recommended Oil
Below 40°F	5W-30 synthetic
40°F to 100°F	10W-30
Above 100°F	SAE 30

For year-round use in most climates, 10W-30 works fine. While you’re doing maintenance, check the air filter and spark plug too. Synthetic oil costs more but provides better protection in extreme temperatures.

Tools Needed

Required:

• 48 oz 10W-30 engine oil
• Oil drain pan
• 15mm wrench or socket
• Shop towels
• Funnel

For filter change:

• Oil filter (John Deere AM125424 or Briggs 492932S)
• Oil filter wrench

Helpful:

• Cardboard to protect the floor
• Nitrile gloves
• Oil dry or cat litter for spills

Oil Drain Procedure

Step 1: Prepare the Mower

1. Run the engine for 3-5 minutes to warm the oil
2. Park on a flat, level surface
3. Engage the parking brake
4. Turn off the engine and remove the key
5. Disconnect the spark plug wire

Warm oil drains faster and carries more contaminants out with it.

Step 2: Locate the Drain Plug

The oil drain plug sits on the bottom-left side of the engine block. On S100 models, it’s accessible from the left side without removing any panels.

Some models have a plastic drain tube that extends downward. If yours has this, you can attach a hose to direct oil into your drain pan.

Step 3: Drain the Oil

1. Position drain pan under the plug
2. Remove the drain plug with a 15mm socket
3. Let oil drain completely (5-10 minutes)
4. Inspect the drain plug gasket
5. Reinstall the plug and tighten snugly

Torque spec: 15-20 ft-lbs. Don’t overtighten—you’ll strip the aluminum threads.

Step 4: Clean Up

Wipe any spilled oil from the engine and frame. Oil left on surfaces attracts dirt and can hide future leaks.

Replacing the Oil Filter

Change the filter every 100 hours or every other oil change. On the S100 series, the filter is on the front-left side of the engine.

Filter Location

The oil filter threads onto a mount on the engine block. It’s a spin-on canister type, same as automotive filters.

Compatible filters:

• John Deere AM125424 (OEM)
• Briggs & Stratton 492932S
• WIX 51056
• NAPA 1056

Filter Replacement Steps

1. Place drain pan under filter
2. Turn filter counterclockwise to remove
3. Let residual oil drain
4. Apply thin coat of fresh oil to new filter gasket
5. Thread new filter on by hand until gasket contacts
6. Tighten 3/4 turn past gasket contact
7. Do not use a wrench to tighten—hand tight plus 3/4 turn is enough

Over-tightening the filter makes removal difficult and can damage the gasket.

How to Refill Oil

Adding Oil

1. Remove the oil fill cap/dipstick
2. Add approximately 44 oz of oil (leave room to check)
3. Wait 30 seconds for oil to settle
4. Check dipstick level
5. Add small amounts until level reaches FULL mark

The dipstick has two marks—ADD and FULL. Keep the level between these marks, closer to FULL.

Checking the Level

1. Remove dipstick and wipe clean
2. Reinsert fully and remove again
3. Read oil level on the stick
4. Level should be at or just below FULL

Important: Check oil on a level surface with the engine off for accurate readings.

First Start After Oil Change

1. Reconnect the spark plug wire
2. Start the engine and let it idle for 30 seconds
3. Check around the drain plug and filter for leaks
4. Shut off and recheck the oil level
5. Top off if needed

The filter fills with oil on first start, which can drop the level slightly.

First Oil Change for Your S100

New John Deere S100 mowers need their first oil change earlier than normal.

Break-In Period

First oil change: After 5-8 hours of operation

New engines shed metal particles during break-in. Changing oil early removes these particles before they cause wear.

After the first change, follow the normal 50-hour interval.

What to Expect

The first oil change will look darker and may have a slight metallic sheen. This is normal. If you see actual metal flakes or chunks, contact your dealer.

When to Change Oil

Interval	Service
Every use	Check oil level
5-8 hours	First oil change (new mowers)
50 hours	Oil change
100 hours	Oil and filter change
End of season	Oil change before storage

Changing oil before winter storage prevents acids in used oil from damaging engine internals during the off-season.

Common Issues During Oil Change

Oil Level Drops Between Changes

Causes:

• External leak at drain plug or filter
• Valve seal wear (blue smoke on startup)
• Ring wear (blue smoke under load)

A small amount of consumption is normal. More than 1/4 quart between changes indicates a problem.

Oil Looks Milky

Water contamination from a blown head gasket or condensation. If it doesn’t clear up after running the engine hot for 20 minutes, have the engine inspected.

Oil Pressure Light Stays On

Stop the engine immediately. Check oil level first. If level is correct, there may be an oil pump or sensor issue.

Related Guides

• John Deere S100 Problems
• John Deere Lawn Mower Parts Diagram
• Lawn Mower Oil Change Guide
• Small Engine Oil Guide

Summary

The John Deere S100 oil change is straightforward with basic tools. Use 10W-30 oil, change every 50 hours and don’t forget the first early change on new mowers. Keep the filter fresh every 100 hours. Regular oil changes are the single best thing you can do for engine longevity.