What is the Eaton Fuller RT-18?
RT-18 is Eaton’s 18-speed manual family, separate from Endurant’s automated 18-speed offerings. Eaton’s service material warns that a 13-speed must not be treated as an 18-speed merely by changing its air controls. Model identification and internal specification matter.
What matters in a comparison
For an RT-18 truck, establish why the job needs that gearbox configuration and confirm the complete vehicle approval. Evaluate condition and service records rather than relying on a gear-count preference. If the transmission has been replaced, ask for the replacement model code and installation documentation. Retain the correct operating and service references; this profile is not a shifting or conversion procedure.
Fluids & filters
Fuller RT 18-speed North American transmission family; the full model code and installed options govern parts selection.
Reference checked:
Identify the unit first
Use these details to match the manufacturer's application record before choosing a fluid or ordering a filter.
- Complete transmission model code
- Transmission serial number
- Installed oil filter/cooler/PTO arrangement
- Service duty and current lubricant specification
Fluid specifications
Transmission lubricant
Eaton-approved PS-386 synthetic transmission lubricant.
For Fuller RT 18-speed applications covered by the OEM references; verify the approved-product label.
Source 1 ↗Filter numbers & cross-references
A catalogue cross-reference links part numbers. It does not confirm that either part fits every version of this model. Match the original part to the unit first, then check the replacement manufacturer's application and any supersession.
Optional transmission-oil filter
Cross-reference only: first confirm that the installed assembly’s correct OE service filter is 4304827 using the model/serial parts catalogue. This does not establish that every Fuller RT 18-speed has this filter.
Application not established by this cross-reference. Confirm this original part number in the manufacturer’s parts catalogue for the exact model and serial number before considering an alternate.
Source 1 ↗ Source 2 ↗Manufacturer catalogue cross-references
- Baldwin BT223Check catalogue ↗
Official service and parts reference ↗
What still needs unit-specific confirmation
- Oil-filter provision varies by transmission and cooler/PTO arrangement. No filter is recommended from gear count alone.
Official service and parts references
Source 1 ↗ Source 2 ↗ Source 3 ↗ Source 4 ↗Follow the current manufacturer's manual for the identified unit. This page does not set a drain interval, fill quantity or repair procedure.
Questions to take to the supplier
- Is the installed model confirmed as an RT-18?
- Are replacement or rebuild records available?
- Which rating and driveline combination were approved?
Sources & limits
Manufacturer material supports the identification and overview above. Comparison considerations and supplier questions are Truck University’s original editorial interpretation, prepared with AI assistance. They are not an independent performance test or expert inspection.
Model-family reference only. Availability, specifications and service requirements can differ by year, market and configuration. Verify the actual vehicle or component using its identification and current manufacturer documentation. Do not use this page as a parts-fitment, modification, repair or loading instruction.
Published specifications and examples retain their labelled units; the header preferences apply to calculators.
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