Most drivers picture synthetic oil as something cooked up in a lab, safely walled off from the crude market. It’s an easy assumption to make, and it’s mostly wrong. The stuff in a jug labeled “full synthetic” usually starts life in a refinery, and a big share of the refineries that make it for the U.S. market are either offline or can’t ship right now. The result: fewer jugs on shelves, purchase limits at warehouse clubs, and oil-change prices climbing again.
Where your “synthetic” oil actually comes from
The key ingredient is Group III base oil, a heavily hydroprocessed petroleum stock that most synthetic motor oils are built on. The Independent Lubricant Manufacturers Association (ILMA), the trade group for independent blenders, says base oil makes up roughly 75% of a finished engine oil, with additives making up the rest, according to ILMA’s customer brief. Base oil also serves as the carrier for those additives. When base oil gets expensive, the whole bottle gets expensive.
The supply problem is concentrated. Three Persian Gulf producers, Pearl GTL in Qatar, ADNOC in the UAE, and BAPCO in Bahrain, supply about 44% of U.S. Group III base oil. The disruption in the Strait of Hormuz has effectively shut down their exports, and Pearl GTL was physically damaged in March.
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“GTL” stands for gas-to-liquids, a process that turns natural gas into very pure base stocks. So some of the most refined synthetic oil you can buy started as Qatari natural gas, not crude. That’s fun trivia right up until the plant that makes it gets hit.
Why the usual fixes aren’t working
ILMA describes three problems hitting at once, and each one blocks a usual backup plan.
South Korean refiners supply around 30% of U.S. Group III base oil, but they depend on Middle East crude, which is also constrained. On top of that, with Asian diesel and jet fuel margins at multi-year highs, those refiners are sending their feedstock to fuels instead of base oil.
The normal fallback is Group II base oil, a less-refined grade that blenders use when Group III gets tight. That option is closed too. With diesel margins at what ILMA calls 40-year highs, refiners are turning vacuum gas oil into fuel, and ILMA says Group II is trading below diesel for the first time on record.
All told, ILMA estimates about 74% of U.S. Group III imports are under direct stress, with the Group II fallback effectively unavailable. A refinery makes more money turning crude into the fuel for your tank than into the oil for your crankcase, so guess which one it’s making.
The rulebook bent, too
The change that affects what’s actually in your engine got much less attention. In March, the American Petroleum Institute (API) activated Emergency Provisional Licensing for companies in its engine-oil certification program, after concluding that the base-oil supply situation met its force majeure threshold, according to ILMA’s EPL announcement.
Under that emergency license, a licensed blender can substitute base oils or other components that it can’t get and still sell the product with the API certification mark. Each license lasts up to 90 days, and API can extend it.
There are safeguards. A blender has to provide technical data showing the substitute won’t hurt the product’s claimed performance, assign a new traceability code to any modified product, and submit test results within 180 days. ILMA has also pushed back on a claim that has spread online. It says it never asked for permission to swap Group II base oil into products sold as “synthetic,” and API’s action doesn’t allow a blanket substitution like that.
My take: the bottle you buy this fall may have the same brand, grade, and API mark as the one you bought last year, and still use a different base oil recipe. It still has to meet the same performance standard, so it’s not a lesser oil. But if you do used-oil analysis, keep the lot codes, because a formulation change could make this year’s results hard to compare with last year’s.
The wallet part
On Valvoline’s fiscal third-quarter earnings call in August, management said it expects finished lubricant costs to rise about 60% from March levels, which works out to roughly $5 to $7 more per oil change depending on the oil used, according to the earnings call transcript. The company also said it expects high costs to last at least four to six months after the Strait of Hormuz fully reopens, because the supply chain needs time to rebuild inventory. Note the timing: that’s after the reopening, not starting today.
Retail is tightening too. I checked Costco’s product page for Kirkland Signature 5W-30 full synthetic, and it now carries a limit of one transaction per membership, with a maximum of two units every seven days, per Costco’s listing. When a warehouse club rations a product it normally sells by the pallet, that’s a sign it isn’t confident about the next delivery.
For DIYers, the math is simple: a typical sump holds five to six quarts, and each Costco unit is a two-pack of 5-quart jugs, so two 10-quart packs a week is plenty for almost anyone except a small fleet. The limit is aimed at hoarders and resellers, not at you.
Who gets hit hardest
Owners of newer, fuel-economy-focused engines should pay the most attention. Very thin grades like 0W-16 and 0W-8 need base stocks that stay stable at low viscosity, which is exactly the high-end Group III and GTL material that’s in short supply. If your manual calls for one of those grades, you have fewer substitutes than someone running 5W-30 in an older V8.
Brand-specific specs add another layer. ILMA says it has asked OEMs, including GM, to give blenders enforcement flexibility on proprietary specs such as dexos. So the oil has to meet more than the API standard, and each extra approval narrows the list of products that qualify.
What I’d actually do
Don’t stretch your change interval to save money. A $7 increase in an oil change costs far less than a timing chain or turbo damaged by degraded oil.
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Read your owner’s manual before you need it. Many manuals list acceptable alternate viscosities, often for temperature ranges or market-specific reasons. Know what your manufacturer allows before a shop tells you your usual grade is out of stock.
Save your receipts and part numbers. If an oil-related warranty claim ever comes up, records showing you used an oil that met spec on schedule are your best protection, especially in a year when shops may be substituting products.
Buy one change ahead, not ten. Keeping one oil change’s worth on the shelf is smart planning. Buying a year’s supply is part of what caused the rationing in the first place.
Expect higher prices to last. ILMA and the analysts it cites don’t expect Group III supply or Group II refining economics to fully recover until at least mid-2027. Valvoline’s four-to-six-month lag after the strait reopens points the same way. Plan your budget around “later,” not “soon.”
Is keeping an extra jug or two on the shelf right now just good planning, or is stocking up the reason your store’s synthetic aisle looks picked over? Tell us what you’re seeing where you shop.