OIL LEAK REPAIR

Spots under the car or a burning-oil smell? Where the drip is tells you what is leaking: valve cover, oil pan or rear main seal. Oil leak diagnosis and repair for Rohnert Park, Cotati, Penngrove, Petaluma and Santa Rosa.

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Professional Oil Leak Repair in Rohnert Park, CA

Key Takeaway: Where the drip lands tells you the likely source. Oil on top of the engine with a burning smell points to the valve cover gasket. A spot directly under the engine points to the oil pan gasket, drain plug or filter. Oil where the engine meets the transmission points to the rear main seal, which is a transmission-out repair. A slow seep is usually safe to drive in for a check if you keep the oil topped up. A falling oil level, smoke, or an oil pressure light is not.

Engine oil leaks almost always come from a gasket or seal that has hardened, cracked or worked loose: the valve cover gasket at the top of the engine, the oil pan gasket, drain plug and filter at the bottom, the timing cover and front crankshaft seal at the front, or the rear main seal at the back where the engine bolts to the transmission. Mobil's repair guides name the same suspects. The fix depends entirely on which one it is, so the first job is finding the source.

Rohnert Park Transmission & Auto Repair does oil leak diagnosis and engine gasket repairs, including valve cover service. The standard way to find a source, as Mobil's oil pan guide describes it, is to clean the oily area and follow the trail to its highest point. That matters because oil from a valve cover can run down the engine and look like a rear main seal or oil pan leak. Under California law you get a written estimate naming the parts and the repair before any work starts.

A rear main seal is a different kind of job. Fel-Pro, which makes these seals, says it starts with removing the transmission and flywheel, the same access as the transmission and clutch work this shop is built around. Call and we will tell you whether your car's rear main seal is a job we take on. Drivers come to 305 Laguna Dr from Rohnert Park, Cotati, Penngrove, Petaluma, Santa Rosa and Sebastopol.

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Where Is the Drip? Match the Spot to the Likely Source

Slide a piece of cardboard under the car overnight. In the morning, note where the spot is (front, middle or back of the engine) and its color. That narrows it down before anyone opens the hood. One warning from Mobil: oil from a leaking valve cover can run down the side or back of the engine and look like a leak from somewhere lower, such as the rear main seal or oil pan. The spot tells you where to look, not always where it starts.

Swipe sideways to see the whole table.

Where a car leak shows up, the likely source, and what to do next
Where you see it	Likely source	What to do
Oil on top or sides of the engine, burning smell after driving, smoke at startup	Valve cover gasket. Mobil names an oil-covered valve cover or a burning-oil smell as the telltale signs.	Check the oil level. Book a leak check before oil runs onto the exhaust.
Spot directly under the engine, at its lowest point	Oil pan gasket, a loose drain plug, or an oil filter that is loose or has a cracked gasket (Mobil).	If it started right after an oil change, the plug or filter is the first suspect.
Oil where the engine meets the transmission, toward the middle of the car	Rear main seal, which keeps oil in at the rear of the crankshaft (Fel-Pro). A valve cover leak running down the back of the engine can look the same.	Have it traced before any parts are ordered. This repair means taking the transmission out.
Oil at the front of the engine, behind the crankshaft pulley	Timing cover gasket or front crankshaft seal. Fel-Pro timing cover sets include the front seal for this reason.	Book a leak check. The timing parts sit behind this cover.
Red or brown fluid around the middle of the car	Transmission fluid. AAA describes it as red or brown and says transmission leaks are usually around the middle of the car.	See our transmission services. Low fluid puts the transmission at risk.
Green puddle toward the front	Coolant. Mobil calls a green puddle the usual first sign of a radiator leak.	Cooling system check. Watch the temperature gauge.
Clear, light yellow or light brown fluid near a wheel	Brake fluid, which AAA describes as clear, light brown or light yellow.	Do not drive it. AAA warns that a car losing brake fluid loses its ability to stop.
Clear water under the A/C area or exhaust pipe	Condensation (AAA). This is normal.	Nothing to fix.

Red fluid is a transmission question, and that is our main trade. See transmission services or the fluid leak guide for every other color. Milky oil or oil in the coolant is a different problem from an external leak: see head gasket repair.

Mechanic inspecting the underside of an SUV raised on a two-post lift in a repair shop — With the car on a lift, the underside can be followed from the oil pan back to where the engine meets the transmission, which is how a drip on the driveway gets traced to one gasket or seal.

The Three Big Oil Leak Repairs, and What Each One Involves

Valve cover gasket replacement (top of the engine)

The valve cover gasket sits between the cylinder head and the valve cover and keeps the oil inside. Mobil says time and miles dry it out or crack it, the bolts can work loose, and the cover itself can warp or crack. The signs are an oily valve cover, a burning-oil smell with the engine running, or smoke at startup. Some valve covers only leak while the engine runs. Mobil's first step is to check the bolts are at the specified torque, because over-tightening will not fix a bad gasket. If the gasket has failed, the parts in the way come off (Mobil lists throttle cables, spark plug brackets and PCV hoses), then the new gasket and bolt grommets go on and the bolts are torqued to spec.

Gloved hand unscrewing the oil fill cap on top of a car engine, with fuel lines and wiring around it — The top of the engine, where valve cover leaks start. Oil that seeps here can run down the side or back of the engine, and a loose or worn oil fill cap is one of the smaller leaks we check on the way.

Oil pan gasket, drain plug and filter (bottom of the engine)

The oil pan is the bottom of the engine. Mobil's guide starts with the simple causes: a loose drain plug, a dipstick tube that has come unseated from the block, or an oil filter that is loose or has a cracked gasket. If the oil trail leads to the pan itself, the job grows. On the front-wheel-drive car in Mobil's guide, the splash shield, a bellhousing cover and wheel-well liner pieces came off to reach the bolts, and parts such as exhaust-manifold supports and A/C brackets can be in the way. The pan comes off without prying, which can bend its sealing surface, and is checked for cracks before it goes back on with the new gasket.

Rear main seal replacement (where the engine meets the transmission)

The rear main seal keeps oil from leaking at the rear of the crankshaft. Fel-Pro says one-piece seals became standard around the 1986 model year. Replacing one means removing the transmission and the flywheel, and in some cases the engine. Once the old seal is out, the crankshaft's sealing surface is checked for nicks or a worn groove, because a damaged surface will make the new seal leak too. Fel-Pro sells a repair sleeve for some engines. On a manual car the clutch comes off on the way to the seal, so ask about the clutch while it is out. Call and we will tell you whether your car's rear main seal is a job we take on.

Smaller leaks come from the timing cover and front crankshaft seal, the oil filter housing, oil cooler lines, the oil pressure sensor and the oil fill cap. A bigger engine problem found along the way goes to our engine repair team.

Is It Safe to Drive With an Oil Leak?

Spots, but the dipstick reads full: usually safe to drive in for a check. Keep checking the level until it is fixed, as Mobil advises.
The level keeps dropping: top it up with the oil your owner's manual calls for and book soon. AAA warns that running on low or no oil can cause serious, irreparable engine damage.
Burning smell or smoke from the engine bay: oil is landing on the hot exhaust. Mobil notes the smoke can drift into the cabin. Get it in quickly.
Smoke from under the hood while driving: pull over when it is safe and turn the engine off. The U.S. Fire Administration says not to open the hood if you think there is a fire under it.
Oil pressure warning light: stop the engine and call us. Do not keep driving to see if it goes away.

Hand pulling the yellow engine oil dipstick out of a car engine to check the oil level — The dipstick is the quickest way to tell a slow seep from a leak that needs booking soon: if the level reads full, keep checking it; if it keeps dropping, top it up and call.

What Changes the Cost of an Oil Leak Repair

Which part is leaking. A drain plug or filter is a small job. A valve cover gasket is a top-of-engine job. A rear main seal means the transmission comes out.
Engine layout and access. A V6 or V8 has two cylinder heads and two valve covers to reach. An oil pan can be blocked by shields, brackets or exhaust supports.
Front- or rear-wheel drive. How the transmission comes out decides most of the labor on a rear main seal.
What is found once it is open. A warped valve cover, a cracked pan or a grooved crankshaft surface adds parts.
Work worth doing while it is apart. On a manual car, the clutch and flywheel are already off for a rear main seal.
More than one leak. An older engine can be leaking from two places, and fixing one leaves the other dripping.

Call (707) 584-7727 with the year, make and model and where the spot is, and we will give you a free estimate before any work starts.

Your Rights in California: A Written Estimate Before Any Work

California's Bureau of Automotive Repair says a repair shop must give you a written estimate before doing any work. The estimate must show the total for parts and labor, list the parts, and state the method of repair. The shop has to stick to those parts and that method unless you agree to a change in advance. Some leaks cannot be priced until parts come off. For those, BAR describes a teardown estimate, and the shop must tell you if there is a charge for it. You can also ask for your old parts back, as long as you ask before the work is done.

Why a Small Drip Matters in Sonoma County

Permit Sonoma lists motor oil among the common pollutants found in storm drains and creeks. It also says anything that enters the storm drain system is discharged untreated into the waterbodies people use for swimming, fishing and drinking water. Every drip on a Rohnert Park or Petaluma street washes that way in the first winter rain. Fixing the leak keeps it out.

Oil Spots in the Driveway? Book an Oil Leak Check in Rohnert Park

Tell us where the spot is, its color, and whether you smell burning oil. We are at 305 Laguna Dr in Rohnert Park, Mon–Thu 7:30 AM – 5:00 PM, Fri 7:00 AM – 3:00 PM, a short drive from Cotati, Penngrove, Petaluma, Santa Rosa and Sebastopol.

Call (707) 584-7727 Book online

Sources

Why Choose Our Oil Leak Repair?

✓Oil leak diagnosis and engine gasket repairs, including valve cover service
✓A written estimate listing parts and the repair method before work starts, as California law requires
✓A transmission and clutch shop, so the transmission-out access a rear main seal needs is familiar work
✓Transmission fluid, coolant and brake fluid leaks told apart from engine oil
✓ASE and ATRA certified technicians at 305 Laguna Dr, Rohnert Park
✓A free estimate by phone: call with the year, make and model and where the spot is

Book an Oil Leak Check in Rohnert Park

Call with the year, make and model and tell us where the spot is and what color it is. We will find the source and give you a free estimate before any work starts.

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Frequently Asked Questions About Oil Leak Repair

Can I drive with an oil leak?

A slow seep is usually fine for a short time if you check the dipstick often and keep the oil topped up. Two things make it urgent. The first is a low oil level: AAA warns that running on low or no oil can cause serious, irreparable engine damage. The second is oil landing on a hot exhaust, which burns and can send smoke into the cabin, as Mobil's valve cover guide explains. If you see smoke coming from under the hood, pull over and turn the engine off. The U.S. Fire Administration says not to open the hood if you think there is a fire under it.

Can I drive with a leaking rear main seal?

Often yes, for a while, if the leak is a seep and you keep checking and topping up the oil. The risk is the oil level. A heavy drip can empty the engine faster than you expect, and low oil is what damages engines. On a manual car the clutch sits right behind the seal. Clutch guidance from Schaeffler's LuK brand says leaks must be fixed before a new clutch goes in, or the new clutch can slip. Call and describe the drip, and we will tell you whether to drive it in or have it brought in.

Is it worth fixing a rear main seal leak?

It depends on how fast the oil is going, where it lands, and the car. A spot the size of a coin after a week is different from a puddle every morning. Weigh the labor of taking the transmission out against the oil you are adding and the risk of running low. If the clutch is already due on a manual car, doing both while the transmission is out avoids paying for the same access twice. Call for a written estimate before you decide.

Can you replace a rear main seal without removing the motor?

On most cars, yes. Fel-Pro, which makes rear main seals, says one-piece rear main seals became standard around the 1986 model year. Replacing one starts with removing the transmission and the flywheel. Fel-Pro adds that in some cases the engine has to come out instead. Older two-piece seals are reached by removing the oil pan and the rear main bearing cap.

Are valve cover gasket leaks bad?

They are a common leak and usually not an emergency, but they should not be ignored. Mobil notes that oil leaking from a valve cover can reach a hot exhaust manifold and burn, and the smoke can drift into the cabin. The oil can also run down the side or back of the engine and look like a rear main seal or oil pan leak. Keep an eye on the oil level until it is fixed.

Are valve cover gaskets hard to replace?

On many engines it is a top-of-engine job. Mobil's guide lists what can be in the way, such as throttle cables, spark plug brackets and PCV hoses, before the cover lifts off. The new gasket and grommets go on, and the bolts are tightened to the specified torque. Mobil also notes that over-tightening will not fix a bad gasket.

How do I know if it is oil or transmission fluid?

Look at the color and where it is. AAA describes engine oil as black, amber or brown, and transmission fluid as red or brown, with transmission leaks usually around the middle of the car. Clear water under the A/C or exhaust is normal condensation. AAA lists red, pink or brown for power steering fluid, so a red drip is a transmission or power steering question, and transmissions are this shop's main trade.

How much does oil leak repair cost?

It depends on what is leaking and how much has to come apart to reach it. A loose drain plug or filter is a small job. A valve cover gasket is usually a top-of-engine job. An oil pan gasket can mean removing shields, brackets or exhaust supports. A rear main seal means the transmission comes out. Call (707) 584-7727 with the year, make and model and where the drip is, and we will give you a free estimate.

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